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Current implementations of sync(2) and syncer vnode fsync() VOP uses

Browse source 
mnt_noasync counter to temporary remove MNTK_ASYNC mount option, which
is needed to guarantee a synchronous completion of the initiated i/o
before syscall or VOP return.  Global removal of MNTK_ASYNC option is
harmful because not only i/o started from corresponding thread becomes
synchronous, but all i/o is synchronous on the filesystem which is
initiated during sync(2) or syncer activity.

Instead of removing MNTK_ASYNC from mnt_kern_flag, provide a local
thread flag to disable async i/o for current thread only. Use the
opportunity to move DOINGASYNC() macro into sys/vnode.h and
consistently use it through places which tested for MNTK_ASYNC.

Some testing demonstrated 60-70% improvements in run time for the
metadata-intensive operations on async-mounted UFS volumes, but still
with great deviation due to other reasons.

Reviewed by:	mckusick
Tested by:	scottl
MFC after:	2 weeks
This commit is contained in:
Konstantin Belousov 2012-02-06 11:04:36 +00:00
parent f1cf024599
commit c480f781ea
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=231075
9 changed files with 16 additions and 38 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

3
sys/fs/ext2fs/inode.h
View file

@ -158,9 +158,6 @@ struct indir {
#define VTOI(vp) ((struct inode *)(vp)->v_data)
#define ITOV(ip) ((ip)->i_vnode)
/* Check whether the MNTK_ASYNC flag has been set for a mount point */
#define DOINGASYNC(vp) ((vp)->v_mount->mnt_kern_flag & MNTK_ASYNC)
/* This overlays the fid structure (see mount.h). */
struct ufid {
uint16_t ufid_len; /* Length of structure. */

2
sys/fs/nfsclient/nfs_clvnops.c
View file

@ -1376,7 +1376,7 @@ ncl_writerpc(struct vnode *vp, struct uio *uiop, struct ucred *cred,
if (ret && !error)
error = ret;
}
if (vp->v_mount->mnt_kern_flag & MNTK_ASYNC)
if (DOINGASYNC(vp))
*iomode = NFSWRITE_FILESYNC;
if (error && NFS_ISV4(vp))
error = nfscl_maperr(uiop->uio_td, error, (uid_t)0, (gid_t)0);

13
sys/geom/journal/g_journal.c
View file

@ -2870,7 +2870,7 @@ g_journal_do_switch(struct g_class *classp)
struct mount *mp;
struct bintime bt;
char *mountpoint;
int error, vfslocked;
int error, save, vfslocked;
DROP_GIANT();
g_topology_lock();
@ -2932,10 +2932,7 @@ g_journal_do_switch(struct g_class *classp)
goto next;
}
MNT_ILOCK(mp);
mp->mnt_noasync++;
mp->mnt_kern_flag &= ~MNTK_ASYNC;
MNT_IUNLOCK(mp);
save = curthread_pflags_set(TDP_SYNCIO);
GJ_TIMER_START(1, &bt);
vfs_msync(mp, MNT_NOWAIT);
@ -2950,11 +2947,7 @@ g_journal_do_switch(struct g_class *classp)
mountpoint, error);
}
MNT_ILOCK(mp);
mp->mnt_noasync--;
if ((mp->mnt_flag & MNT_ASYNC) != 0 && mp->mnt_noasync == 0)
mp->mnt_kern_flag |= MNTK_ASYNC;
MNT_IUNLOCK(mp);
curthread_pflags_restore(save);
vn_finished_write(mp);

13
sys/kern/vfs_subr.c
View file

@ -3521,7 +3521,7 @@ sync_fsync(struct vop_fsync_args *ap)
{
struct vnode *syncvp = ap->a_vp;
struct mount *mp = syncvp->v_mount;
int error;
int error, save;
struct bufobj *bo;
/*
@ -3551,17 +3551,10 @@ sync_fsync(struct vop_fsync_args *ap)
vfs_unbusy(mp);
return (0);
}
MNT_ILOCK(mp);
mp->mnt_noasync++;
mp->mnt_kern_flag &= ~MNTK_ASYNC;
MNT_IUNLOCK(mp);
save = curthread_pflags_set(TDP_SYNCIO);
vfs_msync(mp, MNT_NOWAIT);
error = VFS_SYNC(mp, MNT_LAZY);
MNT_ILOCK(mp);
mp->mnt_noasync--;
if ((mp->mnt_flag & MNT_ASYNC) != 0 && mp->mnt_noasync == 0)
mp->mnt_kern_flag |= MNTK_ASYNC;
MNT_IUNLOCK(mp);
curthread_pflags_restore(save);
vn_finished_write(mp);
vfs_unbusy(mp);
return (error);

14
sys/kern/vfs_syscalls.c
View file

@ -134,7 +134,7 @@ sys_sync(td, uap)
struct sync_args *uap;
{
struct mount *mp, *nmp;
int vfslocked;
int save, vfslocked;
mtx_lock(&mountlist_mtx);
for (mp = TAILQ_FIRST(&mountlist); mp != NULL; mp = nmp) {
@ -145,18 +145,10 @@ sys_sync(td, uap)
vfslocked = VFS_LOCK_GIANT(mp);
if ((mp->mnt_flag & MNT_RDONLY) == 0 &&
vn_start_write(NULL, &mp, V_NOWAIT) == 0) {
MNT_ILOCK(mp);
mp->mnt_noasync++;
mp->mnt_kern_flag &= ~MNTK_ASYNC;
MNT_IUNLOCK(mp);
save = curthread_pflags_set(TDP_SYNCIO);
vfs_msync(mp, MNT_NOWAIT);
VFS_SYNC(mp, MNT_NOWAIT);
MNT_ILOCK(mp);
mp->mnt_noasync--;
if ((mp->mnt_flag & MNT_ASYNC) != 0 &&
mp->mnt_noasync == 0)
mp->mnt_kern_flag |= MNTK_ASYNC;
MNT_IUNLOCK(mp);
curthread_pflags_restore(save);
vn_finished_write(mp);
}
VFS_UNLOCK_GIANT(vfslocked);

2
sys/nfsclient/nfs_vnops.c
View file

@ -1448,7 +1448,7 @@ nfs_writerpc(struct vnode *vp, struct uio *uiop, struct ucred *cred,
tsiz -= len;
}
nfsmout:
if (vp->v_mount->mnt_kern_flag & MNTK_ASYNC)
if (DOINGASYNC(vp))
committed = NFSV3WRITE_FILESYNC;
*iomode = committed;
if (error)

2
sys/sys/proc.h
View file

@ -400,7 +400,7 @@ do { \
#define TDP_NOSLEEPING 0x00000100 /* Thread is not allowed to sleep on a sq. */
#define TDP_OWEUPC 0x00000200 /* Call addupc() at next AST. */
#define TDP_ITHREAD 0x00000400 /* Thread is an interrupt thread. */
#define TDP_UNUSED800 0x00000800 /* available. */
#define TDP_SYNCIO 0x00000800 /* Local override, disable async i/o. */
#define TDP_SCHED1 0x00001000 /* Reserved for scheduler private use */
#define TDP_SCHED2 0x00002000 /* Reserved for scheduler private use */
#define TDP_SCHED3 0x00004000 /* Reserved for scheduler private use */

4
sys/sys/vnode.h
View file

@ -538,6 +538,10 @@ void assert_vop_unlocked(struct vnode *vp, const char *str);
*/
#define VCALL(c) ((c)->a_desc->vdesc_call(c))
#define DOINGASYNC(vp) \
(((vp)->v_mount->mnt_kern_flag & MNTK_ASYNC) != 0 && \
((curthread->td_pflags & TDP_SYNCIO) == 0))
/*
* VMIO support inline
*/

1
sys/ufs/ufs/inode.h
View file

@ -176,7 +176,6 @@ struct indir {
/* Determine if soft dependencies are being done */
#define DOINGSOFTDEP(vp) ((vp)->v_mount->mnt_flag & (MNT_SOFTDEP | MNT_SUJ))
#define MOUNTEDSOFTDEP(mp) ((mp)->mnt_flag & (MNT_SOFTDEP | MNT_SUJ))
#define DOINGASYNC(vp) ((vp)->v_mount->mnt_kern_flag & MNTK_ASYNC)
#define DOINGSUJ(vp) ((vp)->v_mount->mnt_flag & MNT_SUJ)
#define MOUNTEDSUJ(mp) ((mp)->mnt_flag & MNT_SUJ)