svn commit: r362460 - in head/sys: compat/cloudabi fs/devfs kern sys
Thomas Munro
tmunro at FreeBSD.org
Sun Jun 21 08:51:26 UTC 2020
Author: tmunro
Date: Sun Jun 21 08:51:24 2020
New Revision: 362460
URL: https://svnweb.freebsd.org/changeset/base/362460
Log:
vfs: track sequential reads and writes separately
For software like PostgreSQL and SQLite that sometimes reads sequentially
while also writing sequentially some distance behind with interleaved
syscalls on the same fd, performance is better on UFS if we do
sequential access heuristics separately for reads and writes.
Patch originally by Andrew Gierth in 2008, updated and proposed by me with
his permission.
Reviewed by: mjg, kib, tmunro
Approved by: mjg (mentor)
Obtained from: Andrew Gierth <andrew at tao11.riddles.org.uk>
Differential Revision: https://reviews.freebsd.org/D25024
Modified:
head/sys/compat/cloudabi/cloudabi_file.c
head/sys/fs/devfs/devfs_vnops.c
head/sys/kern/kern_descrip.c
head/sys/kern/vfs_syscalls.c
head/sys/kern/vfs_vnops.c
head/sys/sys/file.h
Modified: head/sys/compat/cloudabi/cloudabi_file.c
==============================================================================
--- head/sys/compat/cloudabi/cloudabi_file.c Sun Jun 21 04:59:02 2020 (r362459)
+++ head/sys/compat/cloudabi/cloudabi_file.c Sun Jun 21 08:51:24 2020 (r362460)
@@ -287,7 +287,8 @@ cloudabi_sys_file_open(struct thread *td,
/* Install vnode operations if no custom operations are provided. */
if (fp->f_ops == &badfileops) {
- fp->f_seqcount = 1;
+ fp->f_seqcount[UIO_READ] = 1;
+ fp->f_seqcount[UIO_WRITE] = 1;
finit(fp, (fflags & FMASK) | (fp->f_flag & FHASLOCK),
DTYPE_VNODE, vp, &vnops);
}
Modified: head/sys/fs/devfs/devfs_vnops.c
==============================================================================
--- head/sys/fs/devfs/devfs_vnops.c Sun Jun 21 04:59:02 2020 (r362459)
+++ head/sys/fs/devfs/devfs_vnops.c Sun Jun 21 08:51:24 2020 (r362460)
@@ -1305,7 +1305,7 @@ devfs_read_f(struct file *fp, struct uio *uio, struct
td->td_fpop = fpop;
dev_relthread(dev, ref);
- foffset_unlock_uio(fp, uio, flags | FOF_NOLOCK | FOF_NEXTOFF);
+ foffset_unlock_uio(fp, uio, flags | FOF_NOLOCK | FOF_NEXTOFF_R);
return (error);
}
@@ -1802,7 +1802,7 @@ devfs_write_f(struct file *fp, struct uio *uio, struct
td->td_fpop = fpop;
dev_relthread(dev, ref);
- foffset_unlock_uio(fp, uio, flags | FOF_NOLOCK | FOF_NEXTOFF);
+ foffset_unlock_uio(fp, uio, flags | FOF_NOLOCK | FOF_NEXTOFF_W);
return (error);
}
Modified: head/sys/kern/kern_descrip.c
==============================================================================
--- head/sys/kern/kern_descrip.c Sun Jun 21 04:59:02 2020 (r362459)
+++ head/sys/kern/kern_descrip.c Sun Jun 21 08:51:24 2020 (r362460)
@@ -795,7 +795,7 @@ kern_fcntl(struct thread *td, int fd, int cmd, intptr_
if (arg >= 0) {
bsize = fp->f_vnode->v_mount->mnt_stat.f_iosize;
arg = MIN(arg, INT_MAX - bsize + 1);
- fp->f_seqcount = MIN(IO_SEQMAX,
+ fp->f_seqcount[UIO_READ] = MIN(IO_SEQMAX,
(arg + bsize - 1) / bsize);
atomic_set_int(&fp->f_flag, FRDAHEAD);
} else {
Modified: head/sys/kern/vfs_syscalls.c
==============================================================================
--- head/sys/kern/vfs_syscalls.c Sun Jun 21 04:59:02 2020 (r362459)
+++ head/sys/kern/vfs_syscalls.c Sun Jun 21 08:51:24 2020 (r362460)
@@ -1124,7 +1124,8 @@ kern_openat(struct thread *td, int fd, const char *pat
*/
if (fp->f_ops == &badfileops) {
KASSERT(vp->v_type != VFIFO, ("Unexpected fifo."));
- fp->f_seqcount = 1;
+ fp->f_seqcount[UIO_READ] = 1;
+ fp->f_seqcount[UIO_WRITE] = 1;
finit(fp, (flags & FMASK) | (fp->f_flag & FHASLOCK),
DTYPE_VNODE, vp, &vnops);
}
@@ -4442,7 +4443,8 @@ sys_fhopen(struct thread *td, struct fhopen_args *uap)
td->td_dupfd = 0;
#endif
fp->f_vnode = vp;
- fp->f_seqcount = 1;
+ fp->f_seqcount[UIO_READ] = 1;
+ fp->f_seqcount[UIO_WRITE] = 1;
finit(fp, (fmode & FMASK) | (fp->f_flag & FHASLOCK), DTYPE_VNODE, vp,
&vnops);
VOP_UNLOCK(vp);
Modified: head/sys/kern/vfs_vnops.c
==============================================================================
--- head/sys/kern/vfs_vnops.c Sun Jun 21 04:59:02 2020 (r362459)
+++ head/sys/kern/vfs_vnops.c Sun Jun 21 08:51:24 2020 (r362460)
@@ -489,10 +489,13 @@ vn_close(struct vnode *vp, int flags, struct ucred *fi
static int
sequential_heuristic(struct uio *uio, struct file *fp)
{
+ enum uio_rw rw;
ASSERT_VOP_LOCKED(fp->f_vnode, __func__);
+
+ rw = uio->uio_rw;
if (fp->f_flag & FRDAHEAD)
- return (fp->f_seqcount << IO_SEQSHIFT);
+ return (fp->f_seqcount[rw] << IO_SEQSHIFT);
/*
* Offset 0 is handled specially. open() sets f_seqcount to 1 so
@@ -501,8 +504,8 @@ sequential_heuristic(struct uio *uio, struct file *fp)
* unless previous seeks have reduced f_seqcount to 0, in which
* case offset 0 is not special.
*/
- if ((uio->uio_offset == 0 && fp->f_seqcount > 0) ||
- uio->uio_offset == fp->f_nextoff) {
+ if ((uio->uio_offset == 0 && fp->f_seqcount[rw] > 0) ||
+ uio->uio_offset == fp->f_nextoff[rw]) {
/*
* f_seqcount is in units of fixed-size blocks so that it
* depends mainly on the amount of sequential I/O and not
@@ -513,20 +516,20 @@ sequential_heuristic(struct uio *uio, struct file *fp)
* to any block size used by software.
*/
if (uio->uio_resid >= IO_SEQMAX * 16384)
- fp->f_seqcount = IO_SEQMAX;
+ fp->f_seqcount[rw] = IO_SEQMAX;
else {
- fp->f_seqcount += howmany(uio->uio_resid, 16384);
- if (fp->f_seqcount > IO_SEQMAX)
- fp->f_seqcount = IO_SEQMAX;
+ fp->f_seqcount[rw] += howmany(uio->uio_resid, 16384);
+ if (fp->f_seqcount[rw] > IO_SEQMAX)
+ fp->f_seqcount[rw] = IO_SEQMAX;
}
- return (fp->f_seqcount << IO_SEQSHIFT);
+ return (fp->f_seqcount[rw] << IO_SEQSHIFT);
}
/* Not sequential. Quickly draw-down sequentiality. */
- if (fp->f_seqcount > 1)
- fp->f_seqcount = 1;
+ if (fp->f_seqcount[rw] > 1)
+ fp->f_seqcount[rw] = 1;
else
- fp->f_seqcount = 0;
+ fp->f_seqcount[rw] = 0;
return (0);
}
@@ -734,8 +737,10 @@ foffset_unlock(struct file *fp, off_t val, int flags)
if ((flags & FOF_NOUPDATE) == 0)
atomic_store_long(&fp->f_offset, val);
- if ((flags & FOF_NEXTOFF) != 0)
- fp->f_nextoff = val;
+ if ((flags & FOF_NEXTOFF_R) != 0)
+ fp->f_nextoff[UIO_READ] = val;
+ if ((flags & FOF_NEXTOFF_W) != 0)
+ fp->f_nextoff[UIO_WRITE] = val;
if ((flags & FOF_NOLOCK) != 0)
return;
@@ -788,8 +793,10 @@ foffset_unlock(struct file *fp, off_t val, int flags)
mtx_lock(mtxp);
if ((flags & FOF_NOUPDATE) == 0)
fp->f_offset = val;
- if ((flags & FOF_NEXTOFF) != 0)
- fp->f_nextoff = val;
+ if ((flags & FOF_NEXTOFF_R) != 0)
+ fp->f_nextoff[UIO_READ] = val;
+ if ((flags & FOF_NEXTOFF_W) != 0)
+ fp->f_nextoff[UIO_WRITE] = val;
if ((flags & FOF_NOLOCK) == 0) {
KASSERT((fp->f_vnread_flags & FOFFSET_LOCKED) != 0,
("Lost FOFFSET_LOCKED"));
@@ -878,7 +885,7 @@ vn_read(struct file *fp, struct uio *uio, struct ucred
if (error == 0)
#endif
error = VOP_READ(vp, uio, ioflag, fp->f_cred);
- fp->f_nextoff = uio->uio_offset;
+ fp->f_nextoff[UIO_READ] = uio->uio_offset;
VOP_UNLOCK(vp);
if (error == 0 && advice == POSIX_FADV_NOREUSE &&
orig_offset != uio->uio_offset)
@@ -953,7 +960,7 @@ vn_write(struct file *fp, struct uio *uio, struct ucre
if (error == 0)
#endif
error = VOP_WRITE(vp, uio, ioflag, fp->f_cred);
- fp->f_nextoff = uio->uio_offset;
+ fp->f_nextoff[UIO_WRITE] = uio->uio_offset;
VOP_UNLOCK(vp);
if (vp->v_type != VCHR)
vn_finished_write(mp);
Modified: head/sys/sys/file.h
==============================================================================
--- head/sys/sys/file.h Sun Jun 21 04:59:02 2020 (r362459)
+++ head/sys/sys/file.h Sun Jun 21 08:51:24 2020 (r362460)
@@ -81,7 +81,8 @@ struct ucred;
#define FOF_OFFSET 0x01 /* Use the offset in uio argument */
#define FOF_NOLOCK 0x02 /* Do not take FOFFSET_LOCK */
-#define FOF_NEXTOFF 0x04 /* Also update f_nextoff */
+#define FOF_NEXTOFF_R 0x04 /* Also update f_nextoff[UIO_READ] */
+#define FOF_NEXTOFF_W 0x08 /* Also update f_nextoff[UIO_WRITE] */
#define FOF_NOUPDATE 0x10 /* Do not update f_offset */
off_t foffset_lock(struct file *fp, int flags);
void foffset_lock_uio(struct file *fp, struct uio *uio, int flags);
@@ -187,10 +188,10 @@ struct file {
* DTYPE_VNODE specific fields.
*/
union {
- int16_t f_seqcount; /* (a) Count of sequential accesses. */
+ int16_t f_seqcount[2]; /* (a) Count of seq. reads and writes. */
int f_pipegen;
};
- off_t f_nextoff; /* next expected read/write offset. */
+ off_t f_nextoff[2]; /* next expected read/write offset. */
union {
struct cdev_privdata *fvn_cdevpriv;
/* (d) Private data for the cdev. */
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