Date: Tue, 05 Feb 2008 16:40:12 +0200 From: Andriy Gapon <avg@icyb.net.ua> To: pav@FreeBSD.org Cc: Bruce Evans <bde@zeta.org.au>, freebsd-hackers@FreeBSD.org, scottl@FreeBSD.org, freebsd-fs@FreeBSD.org, Julian Elischer <julian@elischer.org>, Remko Lodder <remko@FreeBSD.org> Subject: Re: fs/udf: vm pages "overlap" while reading large dir [patch] Message-ID: <47A8754C.5010607@icyb.net.ua> In-Reply-To: <1202155663.62432.0.camel@ikaros.oook.cz> References: <200612221824.kBMIOhfM049471@freefall.freebsd.org> <47A2EDB0.8000801@icyb.net.ua> <47A2F404.7010208@icyb.net.ua> <47A735A4.3060506@icyb.net.ua> <47A75B47.2040604@elischer.org> <1202155663.62432.0.camel@ikaros.oook.cz>
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on 04/02/2008 22:07 Pav Lucistnik said the following:
> Julian Elischer píše v po 04. 02. 2008 v 10:36 -0800:
>> Andriy Gapon wrote:
>>> More on the problem with reading big directories on UDF.
>> You do realise that you have now made yourself the official
>> maintainer of the UDF file system by submitting a competent
>> and insightful analysis of the problem?
>
> Yay, and can you fix the sequential read performance while you're at it?
> Kthx!
>
Pav,
this was almost trivial :-)
See the attached patch, first hunk is just for consistency.
The code was borrowed from cd9660, only field/variable names are adjusted.
But there is another issue that I also mentioned in the email about
directory reading. It is UDF_INVALID_BMAP case of udf_bmap_internal,
i.e. the case when file data is embedded into a file entry.
This is a special case that needs to be handled differently.
udf_readatoffset() handles it, but the latest udf_read code doesn't.
I have a real UDF filesystem where this type of allocation is used for
small files and those files can not be read.
This is described in Part 4, section 14.6.8 of ECMA-167.
--
Andriy Gapon
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Content-Type: text/x-patch;
name="udf_ra.patch"
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Content-Disposition: inline;
filename="udf_ra.patch"
--- udf_vnops.c.orig 2008-01-29 23:50:49.000000000 +0200
+++ udf_vnops.c 2008-02-05 01:30:23.000000000 +0200
@@ -851,7 +846,7 @@ udf_bmap(struct vop_bmap_args *a)
if (a->a_runb)
*a->a_runb = 0;
- error = udf_bmap_internal(node, a->a_bn * node->udfmp->bsize, &lsector,
+ error = udf_bmap_internal(node, a->a_bn << node->udfmp->bshift, &lsector,
&max_size);
if (error)
return (error);
@@ -859,9 +854,27 @@ udf_bmap(struct vop_bmap_args *a)
/* Translate logical to physical sector number */
*a->a_bnp = lsector << (node->udfmp->bshift - DEV_BSHIFT);
- /* Punt on read-ahead for now */
- if (a->a_runp)
- *a->a_runp = 0;
+ /*
+ * Determine maximum number of readahead blocks following the
+ * requested block.
+ */
+ if (a->a_runp) {
+ off_t fsize;
+ int nblk;
+
+ fsize = le64toh(node->fentry->inf_len);
+ nblk = (fsize >> node->udfmp->bshift) - (a->a_bn + 1);
+ if (nblk <= 0)
+ *a->a_runp = 0;
+ else if (nblk >= (MAXBSIZE >> node->udfmp->bshift))
+ *a->a_runp = (MAXBSIZE >> node->udfmp->bshift) - 1;
+ else
+ *a->a_runp = nblk;
+ }
+
+ if (a->a_runb) {
+ *a->a_runb = 0;
+ }
return (0);
}
--- udf_vfsops.c.orig 2007-03-13 03:50:24.000000000 +0200
+++ udf_vfsops.c 2008-02-05 01:29:10.000000000 +0200
@@ -330,6 +330,11 @@ udf_mountfs(struct vnode *devvp, struct
bo = &devvp->v_bufobj;
+ if (devvp->v_rdev->si_iosize_max != 0)
+ mp->mnt_iosize_max = devvp->v_rdev->si_iosize_max;
+ if (mp->mnt_iosize_max > MAXPHYS)
+ mp->mnt_iosize_max = MAXPHYS;
+
/* XXX: should be M_WAITOK */
MALLOC(udfmp, struct udf_mnt *, sizeof(struct udf_mnt), M_UDFMOUNT,
M_NOWAIT | M_ZERO);
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