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Simplify the sf_buf implementation.  In short, make it a veneer
 over the direct virtual-to-physical mapping.
This commit is contained in:
Alan Cox 2004-04-18 06:24:51 +00:00
parent 00dcaee469
commit c9b7c6e802
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=128388
2 changed files with 15 additions and 73 deletions
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71
sys/alpha/alpha/vm_machdep.c
View File

@ -101,20 +101,6 @@ __FBSDID("$FreeBSD$");
#include <sys/user.h>
static void sf_buf_init(void *arg);
SYSINIT(sock_sf, SI_SUB_MBUF, SI_ORDER_ANY, sf_buf_init, NULL)
/*
* Expanded sf_freelist head. Really an SLIST_HEAD() in disguise, with the
* sf_freelist head with the sf_lock mutex.
*/
static struct {
SLIST_HEAD(, sf_buf) sf_head;
struct mtx sf_lock;
} sf_freelist;
static u_int sf_buf_alloc_want;
/*
* Finish a fork operation, with process p2 nearly set up.
* Copy and update the pcb, set up the stack so that the child
@ -384,69 +370,24 @@ cpu_reset()
}
/*
* Allocate a pool of sf_bufs (sendfile(2) or "super-fast" if you prefer. :-))
*/
static void
sf_buf_init(void *arg)
{
struct sf_buf *sf_bufs;
int i;
mtx_init(&sf_freelist.sf_lock, "sf_bufs list lock", NULL, MTX_DEF);
SLIST_INIT(&sf_freelist.sf_head);
sf_bufs = malloc(nsfbufs * sizeof(struct sf_buf), M_TEMP,
M_NOWAIT | M_ZERO);
for (i = 0; i < nsfbufs; i++)
SLIST_INSERT_HEAD(&sf_freelist.sf_head, &sf_bufs[i], free_list);
sf_buf_alloc_want = 0;
}
/*
* Get an sf_buf from the freelist. Will block if none are available.
* Allocate an sf_buf for the given vm_page. On this machine, however, there
* is no sf_buf object. Instead, an opaque pointer to the given vm_page is
* returned.
*/
struct sf_buf *
sf_buf_alloc(struct vm_page *m, int pri)
{
struct sf_buf *sf;
int error;
mtx_lock(&sf_freelist.sf_lock);
while ((sf = SLIST_FIRST(&sf_freelist.sf_head)) == NULL) {
sf_buf_alloc_want++;
mbstat.sf_allocwait++;
error = msleep(&sf_freelist, &sf_freelist.sf_lock, PVM | pri,
"sfbufa", 0);
sf_buf_alloc_want--;
/*
* If we got a signal, don't risk going back to sleep.
*/
if (error)
break;
}
if (sf != NULL) {
SLIST_REMOVE_HEAD(&sf_freelist.sf_head, free_list);
sf->m = m;
nsfbufsused++;
nsfbufspeak = imax(nsfbufspeak, nsfbufsused);
}
mtx_unlock(&sf_freelist.sf_lock);
return (sf);
return ((struct sf_buf *)m);
}
/*
* Release resources back to the system.
* Free the sf_buf. In fact, do nothing because there are no resources
* associated with the sf_buf.
*/
void
sf_buf_free(struct sf_buf *sf)
{
mtx_lock(&sf_freelist.sf_lock);
SLIST_INSERT_HEAD(&sf_freelist.sf_head, sf, free_list);
nsfbufsused--;
if (sf_buf_alloc_want > 0)
wakeup_one(&sf_freelist);
mtx_unlock(&sf_freelist.sf_lock);
}
/*

17
sys/alpha/include/sf_buf.h
View File

@ -29,29 +29,30 @@
#ifndef _MACHINE_SF_BUF_H_
#define _MACHINE_SF_BUF_H_
#include <sys/queue.h>
#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/vm_page.h>
struct sf_buf {
SLIST_ENTRY(sf_buf) free_list; /* list of free buffer slots */
vm_page_t m; /* currently mapped page */
};
/*
* On this machine, the only purpose for which sf_buf is used is to implement
* an opaque pointer required by the machine-independent parts of the kernel.
* That pointer references the vm_page that is "mapped" by the sf_buf. The
* actual mapping is provided by the direct virtual-to-physical mapping.
*/
struct sf_buf;
static __inline vm_offset_t
sf_buf_kva(struct sf_buf *sf)
{
return (ALPHA_PHYS_TO_K0SEG(sf->m->phys_addr));
return (ALPHA_PHYS_TO_K0SEG(VM_PAGE_TO_PHYS((vm_page_t)sf)));
}
static __inline vm_page_t
sf_buf_page(struct sf_buf *sf)
{
return (sf->m);
return ((vm_page_t)sf);
}
#endif /* !_MACHINE_SF_BUF_H_ */