i386/68719: [usb] USB 2.0 mobil rack+ fat32 performance problem
Dominic Marks
dom at goodforbusiness.co.uk
Sun May 29 08:20:05 PDT 2005
The following reply was made to PR i386/68719; it has been noted by GNATS.
From: Dominic Marks <dom at goodforbusiness.co.uk>
To: Bruce Evans <bde at zeta.org.au>
Cc: freebsd-gnats-submit at FreeBSD.org,
banhalmi at field.hu,
freebsd-fs at FreeBSD.org
Subject: Re: i386/68719: [usb] USB 2.0 mobil rack+ fat32 performance problem
Date: Sun, 29 May 2005 16:12:46 +0100
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On Saturday 28 May 2005 15:40, Dominic Marks wrote:
> On Saturday 28 May 2005 12:13, Dominic Marks wrote:
> > On Saturday 28 May 2005 11:36, Bruce Evans wrote:
>
> <snip>
>
> > > I use the following to improve transfer rates for msdosfs. The patch
> > > is for an old version so it might not apply directly.
> > >
<snip>
> > Thanks! I'll try my three tests again with this patch.
>
> Index: msdosfs_vnops.c
> ===================================================================
> RCS file: /usr/cvs/src/sys/fs/msdosfs/msdosfs_vnops.c,v
> retrieving revision 1.149.2.1
> diff -u -r1.149.2.1 msdosfs_vnops.c
> --- msdosfs_vnops.c 31 Jan 2005 23:25:56 -0000 1.149.2.1
> +++ msdosfs_vnops.c 28 May 2005 14:26:59 -0000
> @@ -607,6 +607,7 @@
> struct uio *a_uio;
> int a_ioflag;
> struct ucred *a_cred;
> + int seqcount;
> } */ *ap;
> {
> int n;
> @@ -615,6 +616,7 @@
> u_long osize;
> int error = 0;
> u_long count;
> + int seqcount;
> daddr_t bn, lastcn;
> struct buf *bp;
> int ioflag = ap->a_ioflag;
> @@ -692,7 +694,7 @@
> */
> if (uio->uio_offset + resid > osize) {
> count = de_clcount(pmp, uio->uio_offset + resid) -
> - de_clcount(pmp, osize);
> + de_clcount(pmp, osize);
> error = extendfile(dep, count, NULL, NULL, 0);
> if (error && (error != ENOSPC || (ioflag & IO_UNIT)))
> goto errexit;
> @@ -700,6 +702,7 @@
> } else
> lastcn = de_clcount(pmp, osize) - 1;
>
> + seqcount = ioflag >> IO_SEQSHIFT;
> do {
> if (de_cluster(pmp, uio->uio_offset) > lastcn) {
> error = ENOSPC;
> @@ -725,7 +728,7 @@
> * then no need to read data from disk.
> */
> bp = getblk(thisvp, bn, pmp->pm_bpcluster, 0, 0, 0);
> - clrbuf(bp);
> + vfs_bio_clrbuf(bp);
> /*
> * Do the bmap now, since pcbmap needs buffers
> * for the fat table. (see msdosfs_strategy)
> @@ -775,6 +778,7 @@
> * without delay. Otherwise do a delayed write because we
> * may want to write somemore into the block later.
> */
> + /*
> if (ioflag & IO_SYNC)
> (void) bwrite(bp);
> else if (n + croffset == pmp->pm_bpcluster)
> @@ -782,6 +786,24 @@
> else
> bdwrite(bp);
> dep->de_flag |= DE_UPDATE;
> + */
> + /*
> + * XXX Patch.
> + */
> + if ((vp->v_mount->mnt_flag & MNT_NOCLUSTERW) == 0)
> + bp->b_flags |= B_CLUSTEROK;
> + if (ioflag & IO_SYNC)
> + (void)bwrite(bp);
> + else if (vm_page_count_severe() ||
> buf_dirty_count_severe()) + bawrite(bp);
> + else if (n + croffset == pmp->pm_bpcluster) {
> + if ((vp->v_mount->mnt_flag & MNT_NOCLUSTERW) == 0)
> + cluster_write(bp, dep->de_FileSize,
> seqcount); + else
> + bawrite(bp);
> + } else
> + bdwrite(bp);
> + dep->de_flag |= DE_UPDATE;
> } while (error == 0 && uio->uio_resid > 0);
>
> /*
>
> Your patch works for me on 5.4-STABLE. It improves write performance
> dramatically. I did another test, reading and writing 1GB chunks of data.
<snip>
> Since the patch is to the _write function is it safe to assume the same
> method could be used to fix read performance if applied properly in the
> correct function?
>
> Cheers,
I have been experimenting in msdosfs_read and I have managed to come up with
something that works, but I'm sure it is flawed. On large file reads it will
improve read performance (see below) - but only after a long period of the
file copy achieving only 3MB/s (see A1). During this time gstat reports the
disc itself is reading at its maximum of around 28MB/s. After a long period
of low throughput, the disc drops to 25MB/s but the actual transfer rate
increases to 25MB/s (see A2).
I've tried to narrow it down to something but I'm mostly in the dark, so I'll
just hand over what I found to work to review. I looked at Bruce's changes to
msdosfs_write and tried to do the same (implement cluster_read) using the
ext2 and ffs _read methods as a how-to. I think I'm reading ahead too far, or
too early. I have been unable to interpret the gstat output during the first
part of the transfer any further.
gstat(8) output at the start (slow, A1), and middle (fast, A2) of a large file
copy between msdosfs/usb drive (da0s1) and ufs2/ata-100 (ad1).
# A1
dT: 0.501 flag_I 500000us sizeof 240 i -1
L(q) ops/s r/s kBps ms/r w/s kBps ms/w %busy Name
14 445 445 28376 24.7 0 0 0.0 99.9| da0
0 28 0 0 0.0 28 3578 1.7 4.8| ad1
0 28 0 0 0.0 28 3578 1.7 4.8| ad1s1
14 445 445 28376 24.9 0 0 0.0 100.0| da0s1
After 30-45 seconds (1GB test file):
# A2
dT: 0.501 flag_I 500000us sizeof 240 i -1
L(q) ops/s r/s kBps ms/r w/s kBps ms/w %busy Name
1 403 403 25428 2.1 0 0 0.0 85.0| da0
0 199 0 0 0.0 199 25532 1.7 34.0| ad1
0 199 0 0 0.0 199 25532 1.7 34.1| ad1s1
1 403 403 25428 2.1 0 0 0.0 85.9| da0s1
The patch which combines Bruce's original patch for msdosfs_write, revised for
current text positions, and my attempts to do the same for msdosfs_read.
%%
Index: msdosfs_vnops.c
===================================================================
RCS file: /usr/cvs/src/sys/fs/msdosfs/msdosfs_vnops.c,v
retrieving revision 1.149.2.1
diff -u -r1.149.2.1 msdosfs_vnops.c
--- msdosfs_vnops.c 31 Jan 2005 23:25:56 -0000 1.149.2.1
+++ msdosfs_vnops.c 29 May 2005 14:10:18 -0000
@@ -517,6 +517,8 @@
int blsize;
int isadir;
int orig_resid;
+ int nblks = 16; /* XXX should be defined, but not here */
+ int crsize;
u_int n;
u_long diff;
u_long on;
@@ -565,14 +567,21 @@
error = bread(pmp->pm_devvp, lbn, blsize, NOCRED, &bp);
} else {
blsize = pmp->pm_bpcluster;
- rablock = lbn + 1;
- if (seqcount > 1 &&
- de_cn2off(pmp, rablock) < dep->de_FileSize) {
- rasize = pmp->pm_bpcluster;
- error = breadn(vp, lbn, blsize,
- &rablock, &rasize, 1, NOCRED, &bp);
+ /* XXX what is the best value for crsize? */
+ crsize = blsize * nblks > MAXBSIZE ? MAXBSIZE : blsize * nblks;
+ if ((vp->v_mount->mnt_flag & MNT_NOCLUSTERR) == 0) {
+ error = cluster_read(vp, dep->de_FileSize, lbn,
+ crsize, NOCRED, uio->uio_resid, seqcount, &bp);
} else {
- error = bread(vp, lbn, blsize, NOCRED, &bp);
+ rablock = lbn + 1;
+ if (seqcount > 1 &&
+ de_cn2off(pmp, rablock) < dep->de_FileSize) {
+ rasize = pmp->pm_bpcluster;
+ error = breadn(vp, lbn, blsize,
+ &rablock, &rasize, 1, NOCRED, &bp);
+ } else {
+ error = bread(vp, lbn, blsize, NOCRED, &bp);
+ }
}
}
if (error) {
@@ -580,14 +589,16 @@
break;
}
on = uio->uio_offset & pmp->pm_crbomask;
- diff = pmp->pm_bpcluster - on;
- n = diff > uio->uio_resid ? uio->uio_resid : diff;
+ diff = blsize * nblks - on;
+ n = blsize * nblks > uio->uio_resid ? uio->uio_resid : blsize * nblks;
diff = dep->de_FileSize - uio->uio_offset;
- if (diff < n)
+ if (diff < n) {
n = diff;
- diff = blsize - bp->b_resid;
- if (diff < n)
+ }
+ diff = blsize * nblks - bp->b_resid;
+ if (diff < n) {
n = diff;
+ }
error = uiomove(bp->b_data + on, (int) n, uio);
brelse(bp);
} while (error == 0 && uio->uio_resid > 0 && n != 0);
@@ -607,6 +618,7 @@
struct uio *a_uio;
int a_ioflag;
struct ucred *a_cred;
+ int seqcount;
} */ *ap;
{
int n;
@@ -615,6 +627,7 @@
u_long osize;
int error = 0;
u_long count;
+ int seqcount;
daddr_t bn, lastcn;
struct buf *bp;
int ioflag = ap->a_ioflag;
@@ -692,7 +705,7 @@
*/
if (uio->uio_offset + resid > osize) {
count = de_clcount(pmp, uio->uio_offset + resid) -
- de_clcount(pmp, osize);
+ de_clcount(pmp, osize);
error = extendfile(dep, count, NULL, NULL, 0);
if (error && (error != ENOSPC || (ioflag & IO_UNIT)))
goto errexit;
@@ -700,6 +713,7 @@
} else
lastcn = de_clcount(pmp, osize) - 1;
+ seqcount = ioflag >> IO_SEQSHIFT;
do {
if (de_cluster(pmp, uio->uio_offset) > lastcn) {
error = ENOSPC;
@@ -725,7 +739,7 @@
* then no need to read data from disk.
*/
bp = getblk(thisvp, bn, pmp->pm_bpcluster, 0, 0, 0);
- clrbuf(bp);
+ vfs_bio_clrbuf(bp);
/*
* Do the bmap now, since pcbmap needs buffers
* for the fat table. (see msdosfs_strategy)
@@ -775,6 +789,7 @@
* without delay. Otherwise do a delayed write because we
* may want to write somemore into the block later.
*/
+ /*
if (ioflag & IO_SYNC)
(void) bwrite(bp);
else if (n + croffset == pmp->pm_bpcluster)
@@ -782,6 +797,24 @@
else
bdwrite(bp);
dep->de_flag |= DE_UPDATE;
+ */
+ /*
+ * XXX Patch.
+ */
+ if ((vp->v_mount->mnt_flag & MNT_NOCLUSTERW) == 0)
+ bp->b_flags |= B_CLUSTEROK;
+ if (ioflag & IO_SYNC)
+ (void)bwrite(bp);
+ else if (vm_page_count_severe() || buf_dirty_count_severe())
+ bawrite(bp);
+ else if (n + croffset == pmp->pm_bpcluster) {
+ if ((vp->v_mount->mnt_flag & MNT_NOCLUSTERW) == 0)
+ cluster_write(bp, dep->de_FileSize, seqcount);
+ else
+ bawrite(bp);
+ } else
+ bdwrite(bp);
+ dep->de_flag |= DE_UPDATE;
} while (error == 0 && uio->uio_resid > 0);
/*
%%
With this patch I can get the following transfer rates:
msdosfs reading
# ls -lh /mnt/random2.file
-rwxr-xr-x 1 root wheel 1.0G May 29 11:24 /mnt/random2.file
# /usr/bin/time -al cp /mnt/random2.file /vol
59.61 real 0.05 user 6.79 sys
632 maximum resident set size
11 average shared memory size
80 average unshared data size
123 average unshared stack size
88 page reclaims
0 page faults
0 swaps
23757 block input operations **
8192 block output operations
0 messages sent
0 messages received
0 signals received
16660 voluntary context switches
10387 involuntary context switches
Average Rate: 15.31MB/s. (Would be higher if not for the slow start)
** This figure is 3x that of the UFS2 operations. This must be a indicator of
what I'm doing wrong, but I don't know what.
msdosfs writing
# /usr/bin/time -al cp /vol/random2.file /mnt
47.33 real 0.03 user 7.13 sys
632 maximum resident set size
12 average shared memory size
85 average unshared data size
130 average unshared stack size
88 page reclaims
0 page faults
0 swaps
8735 block input operations
16385 block output operations
0 messages sent
0 messages received
0 signals received
8856 voluntary context switches
29631 involuntary context switches
Average Rate: 18.79MB/s.
To compare with UFS2 + softupdates on the same system / disc.
ufs2 reading
# /usr/bin/time -al cp /mnt/random2.file /vol
42.39 real 0.02 user 6.61 sys
632 maximum resident set size
12 average shared memory size
87 average unshared data size
133 average unshared stack size
88 page reclaims
0 page faults
0 swaps
8249 block input operations
8193 block output operations
0 messages sent
0 messages received
0 signals received
8246 voluntary context switches
24617 involuntary context switches
Average Rate: 20.89MB/s.
ufs2 writing
# /usr/bin/time -al cp /vol/random2.file /mnt/
47.12 real 0.03 user 6.74 sys
632 maximum resident set size
12 average shared memory size
85 average unshared data size
130 average unshared stack size
88 page reclaims
0 page faults
0 swaps
8260 block input operations
8192 block output operations
0 messages sent
0 messages received
0 signals received
8303 voluntary context switches
24700 involuntary context switches
Average Rate: 19MB/s.
I'd hope that someone could point me in the right direction so I can clean the
patch up, or finish this off themselves and commit it (or something else
which will increase the read/write speed).
Thanks very much,
--
Dominic
GoodforBusiness.co.uk
I.T. Services for SMEs in the UK.
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Index: msdosfs_vnops.c
===================================================================
RCS file: /usr/cvs/src/sys/fs/msdosfs/msdosfs_vnops.c,v
retrieving revision 1.149.2.1
diff -u -r1.149.2.1 msdosfs_vnops.c
--- msdosfs_vnops.c 31 Jan 2005 23:25:56 -0000 1.149.2.1
+++ msdosfs_vnops.c 29 May 2005 14:10:18 -0000
@@ -517,6 +517,8 @@
int blsize;
int isadir;
int orig_resid;
+ int nblks = 16; /* XXX should be defined, but not here */
+ int crsize;
u_int n;
u_long diff;
u_long on;
@@ -565,14 +567,21 @@
error = bread(pmp->pm_devvp, lbn, blsize, NOCRED, &bp);
} else {
blsize = pmp->pm_bpcluster;
- rablock = lbn + 1;
- if (seqcount > 1 &&
- de_cn2off(pmp, rablock) < dep->de_FileSize) {
- rasize = pmp->pm_bpcluster;
- error = breadn(vp, lbn, blsize,
- &rablock, &rasize, 1, NOCRED, &bp);
+ /* XXX what is the best value for crsize? */
+ crsize = blsize * nblks > MAXBSIZE ? MAXBSIZE : blsize * nblks;
+ if ((vp->v_mount->mnt_flag & MNT_NOCLUSTERR) == 0) {
+ error = cluster_read(vp, dep->de_FileSize, lbn,
+ crsize, NOCRED, uio->uio_resid, seqcount, &bp);
} else {
- error = bread(vp, lbn, blsize, NOCRED, &bp);
+ rablock = lbn + 1;
+ if (seqcount > 1 &&
+ de_cn2off(pmp, rablock) < dep->de_FileSize) {
+ rasize = pmp->pm_bpcluster;
+ error = breadn(vp, lbn, blsize,
+ &rablock, &rasize, 1, NOCRED, &bp);
+ } else {
+ error = bread(vp, lbn, blsize, NOCRED, &bp);
+ }
}
}
if (error) {
@@ -580,14 +589,16 @@
break;
}
on = uio->uio_offset & pmp->pm_crbomask;
- diff = pmp->pm_bpcluster - on;
- n = diff > uio->uio_resid ? uio->uio_resid : diff;
+ diff = blsize * nblks - on;
+ n = blsize * nblks > uio->uio_resid ? uio->uio_resid : blsize * nblks;
diff = dep->de_FileSize - uio->uio_offset;
- if (diff < n)
+ if (diff < n) {
n = diff;
- diff = blsize - bp->b_resid;
- if (diff < n)
+ }
+ diff = blsize * nblks - bp->b_resid;
+ if (diff < n) {
n = diff;
+ }
error = uiomove(bp->b_data + on, (int) n, uio);
brelse(bp);
} while (error == 0 && uio->uio_resid > 0 && n != 0);
@@ -607,6 +618,7 @@
struct uio *a_uio;
int a_ioflag;
struct ucred *a_cred;
+ int seqcount;
} */ *ap;
{
int n;
@@ -615,6 +627,7 @@
u_long osize;
int error = 0;
u_long count;
+ int seqcount;
daddr_t bn, lastcn;
struct buf *bp;
int ioflag = ap->a_ioflag;
@@ -692,7 +705,7 @@
*/
if (uio->uio_offset + resid > osize) {
count = de_clcount(pmp, uio->uio_offset + resid) -
- de_clcount(pmp, osize);
+ de_clcount(pmp, osize);
error = extendfile(dep, count, NULL, NULL, 0);
if (error && (error != ENOSPC || (ioflag & IO_UNIT)))
goto errexit;
@@ -700,6 +713,7 @@
} else
lastcn = de_clcount(pmp, osize) - 1;
+ seqcount = ioflag >> IO_SEQSHIFT;
do {
if (de_cluster(pmp, uio->uio_offset) > lastcn) {
error = ENOSPC;
@@ -725,7 +739,7 @@
* then no need to read data from disk.
*/
bp = getblk(thisvp, bn, pmp->pm_bpcluster, 0, 0, 0);
- clrbuf(bp);
+ vfs_bio_clrbuf(bp);
/*
* Do the bmap now, since pcbmap needs buffers
* for the fat table. (see msdosfs_strategy)
@@ -775,6 +789,7 @@
* without delay. Otherwise do a delayed write because we
* may want to write somemore into the block later.
*/
+ /*
if (ioflag & IO_SYNC)
(void) bwrite(bp);
else if (n + croffset == pmp->pm_bpcluster)
@@ -782,6 +797,24 @@
else
bdwrite(bp);
dep->de_flag |= DE_UPDATE;
+ */
+ /*
+ * XXX Patch.
+ */
+ if ((vp->v_mount->mnt_flag & MNT_NOCLUSTERW) == 0)
+ bp->b_flags |= B_CLUSTEROK;
+ if (ioflag & IO_SYNC)
+ (void)bwrite(bp);
+ else if (vm_page_count_severe() || buf_dirty_count_severe())
+ bawrite(bp);
+ else if (n + croffset == pmp->pm_bpcluster) {
+ if ((vp->v_mount->mnt_flag & MNT_NOCLUSTERW) == 0)
+ cluster_write(bp, dep->de_FileSize, seqcount);
+ else
+ bawrite(bp);
+ } else
+ bdwrite(bp);
+ dep->de_flag |= DE_UPDATE;
} while (error == 0 && uio->uio_resid > 0);
/*
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