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Provide more correct sizing of the KVA consumed by a vnode, used by

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the virtvnodes calculation.  Include the size of fs-specific v_data as
the nfs nclnode inline, the NFS nclnode is bigger than either ZFS
znode or UFS inode.  Include the size of namecache_ts and short cache
path element, multiplied by the name cache population factor, again
inline.

Inline defines are used to avoid pollution of the vnode.h with the
subsystem-private objects.  Non-significant unsynchronized changes of
the definitions are fine, we do not care about that precision, and
e.g. ZFS consumes much malloced memory per vnode for reasons
unaccounted in the formula.

Lower the partition of kmem dedicated to vnodes, from 1/7 to 1/10.

The measures reduce vnode cache pressure on kmem and bring the vnode
cache memory use below some apparent thresholds that were exceeded by
r291244 due to more robust vnode reuse.

Reported and tested by:	marius (i386, previous version)
Reviewed by:	bde
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
This commit is contained in:
Konstantin Belousov 2016-02-24 15:15:46 +00:00
parent 23a6c7330c
commit 0791e0c0e7
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=295971
3 changed files with 27 additions and 4 deletions
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2
sys/kern/vfs_cache.c
View File

@ -171,7 +171,7 @@ SYSCTL_ULONG(_debug, OID_AUTO, numcache, CTLFLAG_RD, &numcache, 0,
static u_long numcachehv; /* number of cache entries with vnodes held */
SYSCTL_ULONG(_debug, OID_AUTO, numcachehv, CTLFLAG_RD, &numcachehv, 0,
"Number of namecache entries with vnodes held");
static u_int ncsizefactor = 2;
u_int ncsizefactor = 2;
SYSCTL_UINT(_vfs, OID_AUTO, ncsizefactor, CTLFLAG_RW, &ncsizefactor, 0,
"Size factor for namecache");

27
sys/kern/vfs_subr.c
View File

@ -407,6 +407,27 @@ vnode_fini(void *mem, int size)
rw_destroy(BO_LOCKPTR(bo));
}
/*
* Provide the size of NFS nclnode and NFS fh for calculation of the
* vnode memory consumption. The size is specified directly to
* eliminate dependency on NFS-private header.
*
* Other filesystems may use bigger or smaller (like UFS and ZFS)
* private inode data, but the NFS-based estimation is ample enough.
* Still, we care about differences in the size between 64- and 32-bit
* platforms.
*
* Namecache structure size is heuristically
* sizeof(struct namecache_ts) + CACHE_PATH_CUTOFF + 1.
*/
#ifdef _LP64
#define NFS_NCLNODE_SZ (528 + 64)
#define NC_SZ 148
#else
#define NFS_NCLNODE_SZ (360 + 32)
#define NC_SZ 92
#endif
static void
vntblinit(void *dummy __unused)
{
@ -422,12 +443,12 @@ vntblinit(void *dummy __unused)
* marginal ratio of desiredvnodes to the physical memory size is
* 1:64. However, desiredvnodes is limited by the kernel's heap
* size. The memory required by desiredvnodes vnodes and vm objects
* must not exceed 1/7th of the kernel's heap size.
* must not exceed 1/10th of the kernel's heap size.
*/
physvnodes = maxproc + pgtok(vm_cnt.v_page_count) / 64 +
3 * min(98304 * 16, pgtok(vm_cnt.v_page_count)) / 64;
virtvnodes = vm_kmem_size / (7 * (sizeof(struct vm_object) +
sizeof(struct vnode)));
virtvnodes = vm_kmem_size / (10 * (sizeof(struct vm_object) +
sizeof(struct vnode) + NC_SZ * ncsizefactor + NFS_NCLNODE_SZ));
desiredvnodes = min(physvnodes, virtvnodes);
if (desiredvnodes > MAXVNODES_MAX) {
if (bootverbose)

2
sys/sys/vnode.h
View File

@ -372,6 +372,8 @@ struct vattr {
MALLOC_DECLARE(M_VNODE);
#endif
extern u_int ncsizefactor;
/*
* Convert between vnode types and inode formats (since POSIX.1
* defines mode word of stat structure in terms of inode formats).