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freebsd/sys/kern/subr_mbuf.c
Bosko Milekic 56b602dd6a On the first day of Christmas bde gave to me: 
A [hopefully] conforming style(9) revamp of mb_alloc and related code.
(This was possible due to bde's remarkable patience.)

Submitted by: (in large part) bde
Reviewed by: (the other part) bde
2001-12-23 22:04:08 +00:00

1111 lines
34 KiB
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/*-
* Copyright (c) 2001
* Bosko Milekic <bmilekic@FreeBSD.org>. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $FreeBSD$
*/
#include "opt_param.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/condvar.h>
#include <sys/smp.h>
#include <sys/kernel.h>
#include <sys/sysctl.h>
#include <sys/domain.h>
#include <sys/protosw.h>
#include <vm/vm.h>
#include <vm/vm_kern.h>
#include <vm/vm_extern.h>
/*
* Maximum number of PCPU containers. If you know what you're doing you could
* explicitly define MBALLOC_NCPU to be exactly the number of CPUs on your
* system during compilation, and thus prevent kernel structure bloat.
*
* SMP and non-SMP kernels clearly have a different number of possible CPUs,
* but because we cannot assume a dense array of CPUs, we always allocate
* and traverse PCPU containers up to NCPU amount and merely check for
* CPU availability.
*/
#ifdef MBALLOC_NCPU
#define NCPU MBALLOC_NCPU
#else
#define NCPU MAXCPU
#endif
/*-
* The mbuf allocator is heavily based on Alfred Perlstein's
* (alfred@FreeBSD.org) "memcache" allocator which is itself based
* on concepts from several per-CPU memory allocators. The difference
* between this allocator and memcache is that, among other things:
*
* (i) We don't free back to the map from the free() routine - we leave the
* option of implementing lazy freeing (from a kproc) in the future.
*
* (ii) We allocate from separate sub-maps of kmem_map, thus limiting the
* maximum number of allocatable objects of a given type. Further,
* we handle blocking on a cv in the case that the map is starved and
* we have to rely solely on cached (circulating) objects.
*
* The mbuf allocator keeps all objects that it allocates in mb_buckets.
* The buckets keep a page worth of objects (an object can be an mbuf or an
* mbuf cluster) and facilitate moving larger sets of contiguous objects
* from the per-CPU lists to the main list for the given object. The buckets
* also have an added advantage in that after several moves from a per-CPU
* list to the main list and back to the per-CPU list, contiguous objects
* are kept together, thus trying to put the TLB cache to good use.
*
* The buckets are kept on singly-linked lists called "containers." A container
* is protected by a mutex lock in order to ensure consistency. The mutex lock
* itself is allocated seperately and attached to the container at boot time,
* thus allowing for certain containers to share the same mutex lock. Per-CPU
* containers for mbufs and mbuf clusters all share the same per-CPU
* lock whereas the "general system" containers (i.e., the "main lists") for
* these objects share one global lock.
*/
struct mb_bucket {
SLIST_ENTRY(mb_bucket) mb_blist;
int mb_owner;
int mb_numfree;
void *mb_free[0];
};
struct mb_container {
SLIST_HEAD(mc_buckethd, mb_bucket) mc_bhead;
struct mtx *mc_lock;
int mc_numowner;
u_int mc_starved;
long *mc_types;
u_long *mc_objcount;
u_long *mc_numpgs;
};
struct mb_gen_list {
struct mb_container mb_cont;
struct cv mgl_mstarved;
};
struct mb_pcpu_list {
struct mb_container mb_cont;
};
/*
* Boot-time configurable object counts that will determine the maximum
* number of permitted objects in the mbuf and mcluster cases. In the
* ext counter (nmbcnt) case, it's just an indicator serving to scale
* kmem_map size properly - in other words, we may be allowed to allocate
* more than nmbcnt counters, whereas we will never be allowed to allocate
* more than nmbufs mbufs or nmbclusters mclusters.
* As for nsfbufs, it is used to indicate how many sendfile(2) buffers will be
* allocatable by the sfbuf allocator (found in uipc_syscalls.c)
*/
#ifndef NMBCLUSTERS
#define NMBCLUSTERS (1024 + maxusers * 64)
#endif
#ifndef NMBUFS
#define NMBUFS (nmbclusters * 2)
#endif
#ifndef NSFBUFS
#define NSFBUFS (512 + maxusers * 16)
#endif
#ifndef NMBCNTS
#define NMBCNTS (nmbclusters + nsfbufs)
#endif
int nmbufs;
int nmbclusters;
int nmbcnt;
int nsfbufs;
/*
* Perform sanity checks of tunables declared above.
*/
static void
tunable_mbinit(void *dummy)
{
/*
* This has to be done before VM init.
*/
nmbclusters = NMBCLUSTERS;
TUNABLE_INT_FETCH("kern.ipc.nmbclusters", &nmbclusters);
nmbufs = NMBUFS;
TUNABLE_INT_FETCH("kern.ipc.nmbufs", &nmbufs);
nsfbufs = NSFBUFS;
TUNABLE_INT_FETCH("kern.ipc.nsfbufs", &nsfbufs);
nmbcnt = NMBCNTS;
TUNABLE_INT_FETCH("kern.ipc.nmbcnt", &nmbcnt);
/* Sanity checks */
if (nmbufs < nmbclusters * 2)
nmbufs = nmbclusters * 2;
if (nmbcnt < nmbclusters + nsfbufs)
nmbcnt = nmbclusters + nsfbufs;
}
SYSINIT(tunable_mbinit, SI_SUB_TUNABLES, SI_ORDER_ANY, tunable_mbinit, NULL);
/*
* The freelist structures and mutex locks. The number statically declared
* here depends on the number of CPUs.
*
* We set up in such a way that all the objects (mbufs, clusters)
* share the same mutex lock. It has been established that we do not benefit
* from different locks for different objects, so we use the same lock,
* regardless of object type.
*/
struct mb_lstmngr {
struct mb_gen_list *ml_genlist;
struct mb_pcpu_list *ml_cntlst[NCPU];
struct mb_bucket **ml_btable;
vm_map_t ml_map;
vm_offset_t ml_mapbase;
vm_offset_t ml_maptop;
int ml_mapfull;
u_int ml_objsize;
u_int *ml_wmhigh;
};
static struct mb_lstmngr mb_list_mbuf, mb_list_clust;
static struct mtx mbuf_gen, mbuf_pcpu[NCPU];
/*
* Local macros for internal allocator structure manipulations.
*/
#ifdef SMP
#define MB_GET_PCPU_LIST(mb_lst) (mb_lst)->ml_cntlst[PCPU_GET(cpuid)]
#else
#define MB_GET_PCPU_LIST(mb_lst) (mb_lst)->ml_cntlst[0]
#endif
#define MB_GET_GEN_LIST(mb_lst) (mb_lst)->ml_genlist
#define MB_LOCK_CONT(mb_cnt) mtx_lock((mb_cnt)->mb_cont.mc_lock)
#define MB_UNLOCK_CONT(mb_cnt) mtx_unlock((mb_cnt)->mb_cont.mc_lock)
#define MB_GET_PCPU_LIST_NUM(mb_lst, num) \
(mb_lst)->ml_cntlst[(num)]
#define MB_BUCKET_INDX(mb_obj, mb_lst) \
(int)(((caddr_t)(mb_obj) - (caddr_t)(mb_lst)->ml_mapbase) / PAGE_SIZE)
#define MB_GET_OBJECT(mb_objp, mb_bckt, mb_lst) \
{ \
struct mc_buckethd *_mchd = &((mb_lst)->mb_cont.mc_bhead); \
\
(mb_bckt)->mb_numfree--; \
(mb_objp) = (mb_bckt)->mb_free[((mb_bckt)->mb_numfree)]; \
(*((mb_lst)->mb_cont.mc_objcount))--; \
if ((mb_bckt)->mb_numfree == 0) { \
SLIST_REMOVE_HEAD(_mchd, mb_blist); \
SLIST_NEXT((mb_bckt), mb_blist) = NULL; \
(mb_bckt)->mb_owner |= MB_BUCKET_FREE; \
} \
}
#define MB_PUT_OBJECT(mb_objp, mb_bckt, mb_lst) \
(mb_bckt)->mb_free[((mb_bckt)->mb_numfree)] = (mb_objp); \
(mb_bckt)->mb_numfree++; \
(*((mb_lst)->mb_cont.mc_objcount))++;
#define MB_MBTYPES_INC(mb_cnt, mb_type, mb_num) \
if ((mb_type) != MT_NOTMBUF) \
(*((mb_cnt)->mb_cont.mc_types + (mb_type))) += (mb_num)
#define MB_MBTYPES_DEC(mb_cnt, mb_type, mb_num) \
if ((mb_type) != MT_NOTMBUF) \
(*((mb_cnt)->mb_cont.mc_types + (mb_type))) -= (mb_num)
/*
* Ownership of buckets/containers is represented by integers. The PCPU
* lists range from 0 to NCPU-1. We need a free numerical id for the general
* list (we use NCPU). We also need a non-conflicting free bit to indicate
* that the bucket is free and removed from a container, while not losing
* the bucket's originating container id. We use the highest bit
* for the free marker.
*/
#define MB_GENLIST_OWNER (NCPU)
#define MB_BUCKET_FREE (1 << (sizeof(int) * 8 - 1))
/* Statistics structures for allocator (per-CPU and general). */
static struct mbpstat mb_statpcpu[NCPU + 1];
struct mbstat mbstat;
/* Sleep time for wait code (in ticks). */
static int mbuf_wait = 64;
static u_int mbuf_limit = 512; /* Upper limit on # of mbufs per CPU. */
static u_int clust_limit = 128; /* Upper limit on # of clusters per CPU. */
/*
* Objects exported by sysctl(8).
*/
SYSCTL_DECL(_kern_ipc);
SYSCTL_INT(_kern_ipc, OID_AUTO, nmbclusters, CTLFLAG_RD, &nmbclusters, 0,
"Maximum number of mbuf clusters available");
SYSCTL_INT(_kern_ipc, OID_AUTO, nmbufs, CTLFLAG_RD, &nmbufs, 0,
"Maximum number of mbufs available");
SYSCTL_INT(_kern_ipc, OID_AUTO, nmbcnt, CTLFLAG_RD, &nmbcnt, 0,
"Number used to scale kmem_map to ensure sufficient space for counters");
SYSCTL_INT(_kern_ipc, OID_AUTO, nsfbufs, CTLFLAG_RD, &nsfbufs, 0,
"Maximum number of sendfile(2) sf_bufs available");
SYSCTL_INT(_kern_ipc, OID_AUTO, mbuf_wait, CTLFLAG_RW, &mbuf_wait, 0,
"Sleep time of mbuf subsystem wait allocations during exhaustion");
SYSCTL_UINT(_kern_ipc, OID_AUTO, mbuf_limit, CTLFLAG_RW, &mbuf_limit, 0,
"Upper limit of number of mbufs allowed on each PCPU list");
SYSCTL_UINT(_kern_ipc, OID_AUTO, clust_limit, CTLFLAG_RW, &clust_limit, 0,
"Upper limit of number of mbuf clusters allowed on each PCPU list");
SYSCTL_STRUCT(_kern_ipc, OID_AUTO, mbstat, CTLFLAG_RD, &mbstat, mbstat,
"Mbuf general information and statistics");
SYSCTL_OPAQUE(_kern_ipc, OID_AUTO, mb_statpcpu, CTLFLAG_RD, mb_statpcpu,
sizeof(mb_statpcpu), "S,", "Mbuf allocator per CPU statistics");
/*
* Prototypes of local allocator routines.
*/
static void *mb_alloc_wait(struct mb_lstmngr *, short);
static struct mb_bucket *mb_pop_cont(struct mb_lstmngr *, int,
struct mb_pcpu_list *);
static void mb_reclaim(void);
static void mbuf_init(void *);
/*
* Initial allocation numbers. Each parameter represents the number of buckets
* of each object that will be placed initially in each PCPU container for
* said object.
*/
#define NMB_MBUF_INIT 4
#define NMB_CLUST_INIT 16
/*
* Initialize the mbuf subsystem.
*
* We sub-divide the kmem_map into several submaps; this way, we don't have
* to worry about artificially limiting the number of mbuf or mbuf cluster
* allocations, due to fear of one type of allocation "stealing" address
* space initially reserved for another.
*
* Set up both the general containers and all the PCPU containers. Populate
* the PCPU containers with initial numbers.
*/
MALLOC_DEFINE(M_MBUF, "mbufmgr", "mbuf subsystem management structures");
SYSINIT(mbuf, SI_SUB_MBUF, SI_ORDER_FIRST, mbuf_init, NULL)
void
mbuf_init(void *dummy)
{
struct mb_pcpu_list *pcpu_cnt;
vm_size_t mb_map_size;
int i, j;
/*
* Set up all the submaps, for each type of object that we deal
* with in this allocator.
*/
mb_map_size = (vm_size_t)(nmbufs * MSIZE);
mb_map_size = rounddown(mb_map_size, PAGE_SIZE);
mb_list_mbuf.ml_btable = malloc((unsigned long)mb_map_size / PAGE_SIZE *
sizeof(struct mb_bucket *), M_MBUF, M_NOWAIT);
if (mb_list_mbuf.ml_btable == NULL)
goto bad;
mb_list_mbuf.ml_map = kmem_suballoc(kmem_map,&(mb_list_mbuf.ml_mapbase),
&(mb_list_mbuf.ml_maptop), mb_map_size);
mb_list_mbuf.ml_mapfull = 0;
mb_list_mbuf.ml_objsize = MSIZE;
mb_list_mbuf.ml_wmhigh = &mbuf_limit;
mb_map_size = (vm_size_t)(nmbclusters * MCLBYTES);
mb_map_size = rounddown(mb_map_size, PAGE_SIZE);
mb_list_clust.ml_btable = malloc((unsigned long)mb_map_size / PAGE_SIZE
* sizeof(struct mb_bucket *), M_MBUF, M_NOWAIT);
if (mb_list_clust.ml_btable == NULL)
goto bad;
mb_list_clust.ml_map = kmem_suballoc(kmem_map,
&(mb_list_clust.ml_mapbase), &(mb_list_clust.ml_maptop),
mb_map_size);
mb_list_clust.ml_mapfull = 0;
mb_list_clust.ml_objsize = MCLBYTES;
mb_list_clust.ml_wmhigh = &clust_limit;
/* XXX XXX XXX: mbuf_map->system_map = clust_map->system_map = 1. */
/*
* Allocate required general (global) containers for each object type.
*/
mb_list_mbuf.ml_genlist = malloc(sizeof(struct mb_gen_list), M_MBUF,
M_NOWAIT);
mb_list_clust.ml_genlist = malloc(sizeof(struct mb_gen_list), M_MBUF,
M_NOWAIT);
if ((mb_list_mbuf.ml_genlist == NULL) ||
(mb_list_clust.ml_genlist == NULL))
goto bad;
/*
* Initialize condition variables and general container mutex locks.
*/
mtx_init(&mbuf_gen, "mbuf subsystem general lists lock", 0);
cv_init(&(mb_list_mbuf.ml_genlist->mgl_mstarved), "mbuf pool starved");
cv_init(&(mb_list_clust.ml_genlist->mgl_mstarved),
"mcluster pool starved");
mb_list_mbuf.ml_genlist->mb_cont.mc_lock =
mb_list_clust.ml_genlist->mb_cont.mc_lock = &mbuf_gen;
/*
* Set up the general containers for each object.
*/
mb_list_mbuf.ml_genlist->mb_cont.mc_numowner =
mb_list_clust.ml_genlist->mb_cont.mc_numowner = MB_GENLIST_OWNER;
mb_list_mbuf.ml_genlist->mb_cont.mc_starved =
mb_list_clust.ml_genlist->mb_cont.mc_starved = 0;
mb_list_mbuf.ml_genlist->mb_cont.mc_objcount =
&(mb_statpcpu[MB_GENLIST_OWNER].mb_mbfree);
mb_list_clust.ml_genlist->mb_cont.mc_objcount =
&(mb_statpcpu[MB_GENLIST_OWNER].mb_clfree);
mb_list_mbuf.ml_genlist->mb_cont.mc_numpgs =
&(mb_statpcpu[MB_GENLIST_OWNER].mb_mbpgs);
mb_list_clust.ml_genlist->mb_cont.mc_numpgs =
&(mb_statpcpu[MB_GENLIST_OWNER].mb_clpgs);
mb_list_mbuf.ml_genlist->mb_cont.mc_types =
&(mb_statpcpu[MB_GENLIST_OWNER].mb_mbtypes[0]);
mb_list_clust.ml_genlist->mb_cont.mc_types = NULL;
SLIST_INIT(&(mb_list_mbuf.ml_genlist->mb_cont.mc_bhead));
SLIST_INIT(&(mb_list_clust.ml_genlist->mb_cont.mc_bhead));
/*
* Initialize general mbuf statistics.
*/
mbstat.m_msize = MSIZE;
mbstat.m_mclbytes = MCLBYTES;
mbstat.m_minclsize = MINCLSIZE;
mbstat.m_mlen = MLEN;
mbstat.m_mhlen = MHLEN;
mbstat.m_numtypes = MT_NTYPES;
/*
* Allocate and initialize PCPU containers.
*/
for (i = 0; i < NCPU; i++) {
if (CPU_ABSENT(i))
continue;
mb_list_mbuf.ml_cntlst[i] = malloc(sizeof(struct mb_pcpu_list),
M_MBUF, M_NOWAIT);
mb_list_clust.ml_cntlst[i] = malloc(sizeof(struct mb_pcpu_list),
M_MBUF, M_NOWAIT);
if ((mb_list_mbuf.ml_cntlst[i] == NULL) ||
(mb_list_clust.ml_cntlst[i] == NULL))
goto bad;
mtx_init(&mbuf_pcpu[i], "mbuf PCPU list lock", 0);
mb_list_mbuf.ml_cntlst[i]->mb_cont.mc_lock =
mb_list_clust.ml_cntlst[i]->mb_cont.mc_lock = &mbuf_pcpu[i];
mb_statpcpu[i].mb_active = 1;
mb_list_mbuf.ml_cntlst[i]->mb_cont.mc_numowner =
mb_list_clust.ml_cntlst[i]->mb_cont.mc_numowner = i;
mb_list_mbuf.ml_cntlst[i]->mb_cont.mc_starved =
mb_list_clust.ml_cntlst[i]->mb_cont.mc_starved = 0;
mb_list_mbuf.ml_cntlst[i]->mb_cont.mc_objcount =
&(mb_statpcpu[i].mb_mbfree);
mb_list_clust.ml_cntlst[i]->mb_cont.mc_objcount =
&(mb_statpcpu[i].mb_clfree);
mb_list_mbuf.ml_cntlst[i]->mb_cont.mc_numpgs =
&(mb_statpcpu[i].mb_mbpgs);
mb_list_clust.ml_cntlst[i]->mb_cont.mc_numpgs =
&(mb_statpcpu[i].mb_clpgs);
mb_list_mbuf.ml_cntlst[i]->mb_cont.mc_types =
&(mb_statpcpu[i].mb_mbtypes[0]);
mb_list_clust.ml_cntlst[i]->mb_cont.mc_types = NULL;
SLIST_INIT(&(mb_list_mbuf.ml_cntlst[i]->mb_cont.mc_bhead));
SLIST_INIT(&(mb_list_clust.ml_cntlst[i]->mb_cont.mc_bhead));
/*
* Perform initial allocations.
*/
pcpu_cnt = MB_GET_PCPU_LIST_NUM(&mb_list_mbuf, i);
MB_LOCK_CONT(pcpu_cnt);
for (j = 0; j < NMB_MBUF_INIT; j++) {
if (mb_pop_cont(&mb_list_mbuf, M_DONTWAIT, pcpu_cnt)
== NULL)
goto bad;
}
MB_UNLOCK_CONT(pcpu_cnt);
pcpu_cnt = MB_GET_PCPU_LIST_NUM(&mb_list_clust, i);
MB_LOCK_CONT(pcpu_cnt);
for (j = 0; j < NMB_CLUST_INIT; j++) {
if (mb_pop_cont(&mb_list_clust, M_DONTWAIT, pcpu_cnt)
== NULL)
goto bad;
}
MB_UNLOCK_CONT(pcpu_cnt);
}
return;
bad:
panic("mbuf_init(): failed to initialize mbuf subsystem!");
}
/*
* Populate a given mbuf PCPU container with a bucket full of fresh new
* buffers. Return a pointer to the new bucket (already in the container if
* successful), or return NULL on failure.
*
* LOCKING NOTES:
* PCPU container lock must be held when this is called.
* The lock is dropped here so that we can cleanly call the underlying VM
* code. If we fail, we return with no locks held. If we succeed (i.e., return
* non-NULL), we return with the PCPU lock held, ready for allocation from
* the returned bucket.
*/
static struct mb_bucket *
mb_pop_cont(struct mb_lstmngr *mb_list, int how, struct mb_pcpu_list *cnt_lst)
{
struct mb_bucket *bucket;
caddr_t p;
int i;
MB_UNLOCK_CONT(cnt_lst);
/*
* If our object's (finite) map is starved now (i.e., no more address
* space), bail out now.
*/
if (mb_list->ml_mapfull)
return (NULL);
bucket = malloc(sizeof(struct mb_bucket) +
PAGE_SIZE / mb_list->ml_objsize * sizeof(void *), M_MBUF,
how == M_TRYWAIT ? M_WAITOK : M_NOWAIT);
if (bucket == NULL)
return (NULL);
p = (caddr_t)kmem_malloc(mb_list->ml_map, PAGE_SIZE,
how == M_TRYWAIT ? M_WAITOK : M_NOWAIT);
if (p == NULL) {
free(bucket, M_MBUF);
if (how == M_TRYWAIT)
mb_list->ml_mapfull = 1;
return (NULL);
}
bucket->mb_numfree = 0;
mb_list->ml_btable[MB_BUCKET_INDX(p, mb_list)] = bucket;
for (i = 0; i < (PAGE_SIZE / mb_list->ml_objsize); i++) {
bucket->mb_free[i] = p;
bucket->mb_numfree++;
p += mb_list->ml_objsize;
}
MB_LOCK_CONT(cnt_lst);
bucket->mb_owner = cnt_lst->mb_cont.mc_numowner;
SLIST_INSERT_HEAD(&(cnt_lst->mb_cont.mc_bhead), bucket, mb_blist);
(*(cnt_lst->mb_cont.mc_numpgs))++;
*(cnt_lst->mb_cont.mc_objcount) += bucket->mb_numfree;
return (bucket);
}
/*
* Allocate an mbuf-subsystem type object.
* The general case is very easy. Complications only arise if our PCPU
* container is empty. Things get worse if the PCPU container is empty,
* the general container is empty, and we've run out of address space
* in our map; then we try to block if we're willing to (M_TRYWAIT).
*/
static __inline
void *
mb_alloc(struct mb_lstmngr *mb_list, int how, short type)
{
static int last_report;
struct mb_pcpu_list *cnt_lst;
struct mb_bucket *bucket;
void *m;
m = NULL;
cnt_lst = MB_GET_PCPU_LIST(mb_list);
MB_LOCK_CONT(cnt_lst);
if ((bucket = SLIST_FIRST(&(cnt_lst->mb_cont.mc_bhead))) != NULL) {
/*
* This is the easy allocation case. We just grab an object
* from a bucket in the PCPU container. At worst, we
* have just emptied the bucket and so we remove it
* from the container.
*/
MB_GET_OBJECT(m, bucket, cnt_lst);
MB_MBTYPES_INC(cnt_lst, type, 1);
MB_UNLOCK_CONT(cnt_lst);
} else {
struct mb_gen_list *gen_list;
/*
* This is the less-common more difficult case. We must
* first verify if the general list has anything for us
* and if that also fails, we must allocate a page from
* the map and create a new bucket to place in our PCPU
* container (already locked). If the map is starved then
* we're really in for trouble, as we have to wait on
* the general container's condition variable.
*/
gen_list = MB_GET_GEN_LIST(mb_list);
MB_LOCK_CONT(gen_list);
if ((bucket = SLIST_FIRST(&(gen_list->mb_cont.mc_bhead)))
!= NULL) {
/*
* Give ownership of the bucket to our CPU's
* container, but only actually put the bucket
* in the container if it doesn't become free
* upon removing an mbuf from it.
*/
SLIST_REMOVE_HEAD(&(gen_list->mb_cont.mc_bhead),
mb_blist);
bucket->mb_owner = cnt_lst->mb_cont.mc_numowner;
(*(gen_list->mb_cont.mc_numpgs))--;
(*(cnt_lst->mb_cont.mc_numpgs))++;
*(gen_list->mb_cont.mc_objcount) -= bucket->mb_numfree;
bucket->mb_numfree--;
m = bucket->mb_free[(bucket->mb_numfree)];
if (bucket->mb_numfree == 0) {
SLIST_NEXT(bucket, mb_blist) = NULL;
bucket->mb_owner |= MB_BUCKET_FREE;
} else {
SLIST_INSERT_HEAD(&(cnt_lst->mb_cont.mc_bhead),
bucket, mb_blist);
*(cnt_lst->mb_cont.mc_objcount) +=
bucket->mb_numfree;
}
MB_UNLOCK_CONT(gen_list);
MB_MBTYPES_INC(cnt_lst, type, 1);
MB_UNLOCK_CONT(cnt_lst);
} else {
/*
* We'll have to allocate a new page.
*/
MB_UNLOCK_CONT(gen_list);
bucket = mb_pop_cont(mb_list, how, cnt_lst);
if (bucket != NULL) {
bucket->mb_numfree--;
m = bucket->mb_free[(bucket->mb_numfree)];
(*(cnt_lst->mb_cont.mc_objcount))--;
MB_MBTYPES_INC(cnt_lst, type, 1);
MB_UNLOCK_CONT(cnt_lst);
} else {
if (how == M_TRYWAIT) {
/*
* Absolute worst-case scenario.
* We block if we're willing to, but
* only after trying to steal from
* other lists.
*/
m = mb_alloc_wait(mb_list, type);
} else {
/* XXX: No consistency. */
mbstat.m_drops++;
if (ticks < last_report ||
(ticks - last_report) >= hz) {
last_report = ticks;
printf(
"mb_alloc for mbuf type %d failed.\n", type);
}
}
}
}
}
return (m);
}
/*
* This is the worst-case scenario called only if we're allocating with
* M_TRYWAIT. We first drain all the protocols, then try to find an mbuf
* by looking in every PCPU container. If we're still unsuccesful, we
* try the general container one last time and possibly block on our
* starved cv.
*/
static void *
mb_alloc_wait(struct mb_lstmngr *mb_list, short type)
{
struct mb_pcpu_list *cnt_lst;
struct mb_gen_list *gen_list;
struct mb_bucket *bucket;
void *m;
int i, cv_ret;
/*
* Try to reclaim mbuf-related objects (mbufs, clusters).
*/
mb_reclaim();
/*
* Cycle all the PCPU containers. Increment starved counts if found
* empty.
*/
for (i = 0; i < NCPU; i++) {
if (CPU_ABSENT(i))
continue;
cnt_lst = MB_GET_PCPU_LIST_NUM(mb_list, i);
MB_LOCK_CONT(cnt_lst);
/*
* If container is non-empty, get a single object from it.
* If empty, increment starved count.
*/
if ((bucket = SLIST_FIRST(&(cnt_lst->mb_cont.mc_bhead))) !=
NULL) {
MB_GET_OBJECT(m, bucket, cnt_lst);
MB_MBTYPES_INC(cnt_lst, type, 1);
MB_UNLOCK_CONT(cnt_lst);
mbstat.m_wait++; /* XXX: No consistency. */
return (m);
} else
cnt_lst->mb_cont.mc_starved++;
MB_UNLOCK_CONT(cnt_lst);
}
/*
* We're still here, so that means it's time to get the general
* container lock, check it one more time (now that mb_reclaim()
* has been called) and if we still get nothing, block on the cv.
*/
gen_list = MB_GET_GEN_LIST(mb_list);
MB_LOCK_CONT(gen_list);
if ((bucket = SLIST_FIRST(&(gen_list->mb_cont.mc_bhead))) != NULL) {
MB_GET_OBJECT(m, bucket, gen_list);
MB_MBTYPES_INC(gen_list, type, 1);
MB_UNLOCK_CONT(gen_list);
mbstat.m_wait++; /* XXX: No consistency. */
return (m);
}
gen_list->mb_cont.mc_starved++;
cv_ret = cv_timedwait(&(gen_list->mgl_mstarved),
gen_list->mb_cont.mc_lock, mbuf_wait);
gen_list->mb_cont.mc_starved--;
if ((cv_ret == 0) &&
((bucket = SLIST_FIRST(&(gen_list->mb_cont.mc_bhead))) != NULL)) {
MB_GET_OBJECT(m, bucket, gen_list);
MB_MBTYPES_INC(gen_list, type, 1);
mbstat.m_wait++; /* XXX: No consistency. */
} else {
mbstat.m_drops++; /* XXX: No consistency. */
m = NULL;
}
MB_UNLOCK_CONT(gen_list);
return (m);
}
/*-
* Free an object to its rightful container.
* In the very general case, this operation is really very easy.
* Complications arise primarily if:
* (a) We've hit the high limit on number of free objects allowed in
* our PCPU container.
* (b) We're in a critical situation where our container has been
* marked 'starved' and we need to issue wakeups on the starved
* condition variable.
* (c) Minor (odd) cases: our bucket has migrated while we were
* waiting for the lock; our bucket is in the general container;
* our bucket is empty.
*/
static __inline
void
mb_free(struct mb_lstmngr *mb_list, void *m, short type)
{
struct mb_pcpu_list *cnt_lst;
struct mb_gen_list *gen_list;
struct mb_bucket *bucket;
u_int owner;
bucket = mb_list->ml_btable[MB_BUCKET_INDX(m, mb_list)];
/*
* Make sure that if after we lock the bucket's present container the
* bucket has migrated, that we drop the lock and get the new one.
*/
retry_lock:
owner = bucket->mb_owner & ~MB_BUCKET_FREE;
switch (owner) {
case MB_GENLIST_OWNER:
gen_list = MB_GET_GEN_LIST(mb_list);
MB_LOCK_CONT(gen_list);
if (owner != (bucket->mb_owner & ~MB_BUCKET_FREE)) {
MB_UNLOCK_CONT(gen_list);
goto retry_lock;
}
/*
* If we're intended for the general container, this is
* real easy: no migrating required. The only `bogon'
* is that we're now contending with all the threads
* dealing with the general list, but this is expected.
*/
MB_PUT_OBJECT(m, bucket, gen_list);
MB_MBTYPES_DEC(gen_list, type, 1);
if (gen_list->mb_cont.mc_starved > 0)
cv_signal(&(gen_list->mgl_mstarved));
MB_UNLOCK_CONT(gen_list);
break;
default:
cnt_lst = MB_GET_PCPU_LIST_NUM(mb_list, owner);
MB_LOCK_CONT(cnt_lst);
if (owner != (bucket->mb_owner & ~MB_BUCKET_FREE)) {
MB_UNLOCK_CONT(cnt_lst);
goto retry_lock;
}
MB_PUT_OBJECT(m, bucket, cnt_lst);
MB_MBTYPES_DEC(cnt_lst, type, 1);
if (cnt_lst->mb_cont.mc_starved > 0) {
/*
* This is a tough case. It means that we've
* been flagged at least once to indicate that
* we're empty, and that the system is in a critical
* situation, so we ought to migrate at least one
* bucket over to the general container.
* There may or may not be a thread blocking on
* the starved condition variable, but chances
* are that one will eventually come up soon so
* it's better to migrate now than never.
*/
gen_list = MB_GET_GEN_LIST(mb_list);
MB_LOCK_CONT(gen_list);
KASSERT((bucket->mb_owner & MB_BUCKET_FREE) != 0,
("mb_free: corrupt bucket %p\n", bucket));
SLIST_INSERT_HEAD(&(gen_list->mb_cont.mc_bhead),
bucket, mb_blist);
bucket->mb_owner = MB_GENLIST_OWNER;
(*(cnt_lst->mb_cont.mc_objcount))--;
(*(gen_list->mb_cont.mc_objcount))++;
(*(cnt_lst->mb_cont.mc_numpgs))--;
(*(gen_list->mb_cont.mc_numpgs))++;
/*
* Determine whether or not to keep transferring
* buckets to the general list or whether we've
* transferred enough already.
* We realize that although we may flag another
* bucket to be migrated to the general container
* that in the meantime, the thread that was
* blocked on the cv is already woken up and
* long gone. But in that case, the worst
* consequence is that we will end up migrating
* one bucket too many, which is really not a big
* deal, especially if we're close to a critical
* situation.
*/
if (gen_list->mb_cont.mc_starved > 0) {
cnt_lst->mb_cont.mc_starved--;
cv_signal(&(gen_list->mgl_mstarved));
} else
cnt_lst->mb_cont.mc_starved = 0;
MB_UNLOCK_CONT(gen_list);
MB_UNLOCK_CONT(cnt_lst);
break;
}
if (*(cnt_lst->mb_cont.mc_objcount) > *(mb_list->ml_wmhigh)) {
/*
* We've hit the high limit of allowed numbers of mbufs
* on this PCPU list. We must now migrate a bucket
* over to the general container.
*/
gen_list = MB_GET_GEN_LIST(mb_list);
MB_LOCK_CONT(gen_list);
if ((bucket->mb_owner & MB_BUCKET_FREE) == 0) {
bucket =
SLIST_FIRST(&(cnt_lst->mb_cont.mc_bhead));
SLIST_REMOVE_HEAD(&(cnt_lst->mb_cont.mc_bhead),
mb_blist);
}
SLIST_INSERT_HEAD(&(gen_list->mb_cont.mc_bhead),
bucket, mb_blist);
bucket->mb_owner = MB_GENLIST_OWNER;
*(cnt_lst->mb_cont.mc_objcount) -= bucket->mb_numfree;
*(gen_list->mb_cont.mc_objcount) += bucket->mb_numfree;
(*(cnt_lst->mb_cont.mc_numpgs))--;
(*(gen_list->mb_cont.mc_numpgs))++;
/*
* While we're at it, transfer some of the mbtypes
* "count load" onto the general list's mbtypes
* array, seeing as how we're moving the bucket
* there now, meaning that the freeing of objects
* there will now decrement the _general list's_
* mbtypes counters, and no longer our PCPU list's
* mbtypes counters. We do this for the type presently
* being freed in an effort to keep the mbtypes
* counters approximately balanced across all lists.
*/
MB_MBTYPES_DEC(cnt_lst, type, (PAGE_SIZE /
mb_list->ml_objsize) - bucket->mb_numfree);
MB_MBTYPES_INC(gen_list, type, (PAGE_SIZE /
mb_list->ml_objsize) - bucket->mb_numfree);
MB_UNLOCK_CONT(gen_list);
MB_UNLOCK_CONT(cnt_lst);
break;
}
if (bucket->mb_owner & MB_BUCKET_FREE) {
SLIST_INSERT_HEAD(&(cnt_lst->mb_cont.mc_bhead),
bucket, mb_blist);
bucket->mb_owner = cnt_lst->mb_cont.mc_numowner;
}
MB_UNLOCK_CONT(cnt_lst);
break;
}
}
/*
* Drain protocols in hopes to free up some resources.
*
* LOCKING NOTES:
* No locks should be held when this is called. The drain routines have to
* presently acquire some locks which raises the possibility of lock order
* violation if we're holding any mutex if that mutex is acquired in reverse
* order relative to one of the locks in the drain routines.
*/
static void
mb_reclaim(void)
{
struct domain *dp;
struct protosw *pr;
/*
* XXX: Argh, we almost always trip here with witness turned on now-a-days
* XXX: because we often come in with Giant held. For now, there's no way
* XXX: to avoid this.
*/
#ifdef WITNESS
KASSERT(witness_list(curthread) == 0,
("mb_reclaim() called with locks held"));
#endif
mbstat.m_drain++; /* XXX: No consistency. */
for (dp = domains; dp != NULL; dp = dp->dom_next)
for (pr = dp->dom_protosw; pr < dp->dom_protoswNPROTOSW; pr++)
if (pr->pr_drain != NULL)
(*pr->pr_drain)();
}
/*
* Local mbuf & cluster alloc macros and routines.
* Local macro and function names begin with an underscore ("_").
*/
static void _mclfree(struct mbuf *);
#define _m_get(m, how, type) do { \
(m) = (struct mbuf *)mb_alloc(&mb_list_mbuf, (how), (type)); \
if ((m) != NULL) { \
(m)->m_type = (type); \
(m)->m_next = NULL; \
(m)->m_nextpkt = NULL; \
(m)->m_data = (m)->m_dat; \
(m)->m_flags = 0; \
} \
} while (0)
#define _m_gethdr(m, how, type) do { \
(m) = (struct mbuf *)mb_alloc(&mb_list_mbuf, (how), (type)); \
if ((m) != NULL) { \
(m)->m_type = (type); \
(m)->m_next = NULL; \
(m)->m_nextpkt = NULL; \
(m)->m_data = (m)->m_pktdat; \
(m)->m_flags = M_PKTHDR; \
(m)->m_pkthdr.rcvif = NULL; \
(m)->m_pkthdr.csum_flags = 0; \
(m)->m_pkthdr.aux = NULL; \
} \
} while (0)
/* XXX: Check for M_PKTHDR && m_pkthdr.aux is bogus... please fix (see KAME). */
#define _m_free(m, n) do { \
(n) = (m)->m_next; \
if ((m)->m_flags & M_EXT) \
MEXTFREE((m)); \
if (((m)->m_flags & M_PKTHDR) != 0 && (m)->m_pkthdr.aux) { \
m_freem((m)->m_pkthdr.aux); \
(m)->m_pkthdr.aux = NULL; \
} \
mb_free(&mb_list_mbuf, (m), (m)->m_type); \
} while (0)
#define _mext_init_ref(m) do { \
(m)->m_ext.ref_cnt = malloc(sizeof(u_int), M_MBUF, M_NOWAIT); \
if ((m)->m_ext.ref_cnt != NULL) { \
*((m)->m_ext.ref_cnt) = 0; \
MEXT_ADD_REF((m)); \
} \
} while (0)
#define _mext_dealloc_ref(m) \
free((m)->m_ext.ref_cnt, M_MBUF)
void
_mext_free(struct mbuf *mb)
{
if (mb->m_ext.ext_type == EXT_CLUSTER)
mb_free(&mb_list_clust, (caddr_t)mb->m_ext.ext_buf, MT_NOTMBUF);
else
(*(mb->m_ext.ext_free))(mb->m_ext.ext_buf, mb->m_ext.ext_args);
_mext_dealloc_ref(mb);
}
/*
* We only include this here to avoid making m_clget() excessively large
* due to too much inlined code.
*/
static void
_mclfree(struct mbuf *mb)
{
mb_free(&mb_list_clust, (caddr_t)mb->m_ext.ext_buf, MT_NOTMBUF);
mb->m_ext.ext_buf = NULL;
}
/*
* Exported space allocation and de-allocation routines.
*/
struct mbuf *
m_get(int how, int type)
{
struct mbuf *mb;
_m_get(mb, how, type);
return (mb);
}
struct mbuf *
m_gethdr(int how, int type)
{
struct mbuf *mb;
_m_gethdr(mb, how, type);
return (mb);
}
struct mbuf *
m_get_clrd(int how, int type)
{
struct mbuf *mb;
_m_get(mb, how, type);
if (mb != NULL)
bzero(mtod(mb, caddr_t), MLEN);
return (mb);
}
struct mbuf *
m_gethdr_clrd(int how, int type)
{
struct mbuf *mb;
_m_gethdr(mb, how, type);
if (mb != NULL)
bzero(mtod(mb, caddr_t), MHLEN);
return (mb);
}
struct mbuf *
m_free(struct mbuf *mb)
{
struct mbuf *nb;
_m_free(mb, nb);
return (nb);
}
void
m_clget(struct mbuf *mb, int how)
{
mb->m_ext.ext_buf = (caddr_t)mb_alloc(&mb_list_clust, how, MT_NOTMBUF);
if (mb->m_ext.ext_buf != NULL) {
_mext_init_ref(mb);
if (mb->m_ext.ref_cnt == NULL)
_mclfree(mb);
else {
mb->m_data = mb->m_ext.ext_buf;
mb->m_flags |= M_EXT;
mb->m_ext.ext_free = NULL;
mb->m_ext.ext_args = NULL;
mb->m_ext.ext_size = MCLBYTES;
mb->m_ext.ext_type = EXT_CLUSTER;
}
}
}
void
m_extadd(struct mbuf *mb, caddr_t buf, u_int size,
void (*freef)(caddr_t, void *), void *args, short flags, int type)
{
_mext_init_ref(mb);
if (mb->m_ext.ref_cnt != NULL) {
mb->m_flags |= (M_EXT | flags);
mb->m_ext.ext_buf = buf;
mb->m_data = mb->m_ext.ext_buf;
mb->m_ext.ext_size = size;
mb->m_ext.ext_free = freef;
mb->m_ext.ext_args = args;
mb->m_ext.ext_type = type;
}
}
/*
* Change type for mbuf `mb'; this is a relatively expensive operation and
* should be avoided.
*/
void
m_chtype(struct mbuf *mb, short new_type)
{
struct mb_gen_list *gen_list;
gen_list = MB_GET_GEN_LIST(&mb_list_mbuf);
MB_LOCK_CONT(gen_list);
MB_MBTYPES_DEC(gen_list, mb->m_type, 1);
MB_MBTYPES_INC(gen_list, new_type, 1);
MB_UNLOCK_CONT(gen_list);
mb->m_type = new_type;
}
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