Date: Mon, 28 Oct 2013 10:17:47 -0000 From: "Steven Hartland" <killing@multiplay.co.uk> To: "Vitalij Satanivskij" <satan@ukr.net> Cc: Vitalij Satanivskij <satan@ukr.net>, freebsd-current@freebsd.org, Dmitriy Makarov <supportme@ukr.net> Subject: Re: ZFS L2ARC - incorrect size and abnormal system load on r255173 Message-ID: <CA8604386CA2477A90B53BC93B6C7192@multiplay.co.uk> References: <20131007185032.GA82932@hell.ukr.net> <20131007211201.GA89306@hell.ukr.net> <20131010092223.GA28347@hell.ukr.net> <5256D9D4.2030308@allanjude.com> <20131010170334.GA71635@hell.ukr.net> <3E3F85F87B0D40C6A776A42786EEF08D@multiplay.co.uk> <20131022141055.GA34810@hell.ukr.net> <5C339A76AE4C402BA5F9F1470500246A@multiplay.co.uk> <20131025073219.GA4086@hell.ukr.net> <96FA3CD4CDCE49268EF41E28FF4E9381@multiplay.co.uk> <20131028090615.GA90738@hell.ukr.net>
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Correct, there's clearly some other cases which sets
ARC_L2COMPRESS on b_flags for write, but I cant see
where unless its some how gets through from the read
cases.
Attached is a patch which removes all paths which
set ARC_L2COMPRESS on b_flags for both read and write.
Revert the last patch and try this one.
To be clear l2_compress_failures are only a failure
to compress the data, which is not an error.
Have you seen any l2_io_error or l2_cksum_bad since
applying the ashift patch?
Regards
Steve
----- Original Message -----
From: "Vitalij Satanivskij" <satan@ukr.net>
>
> So that's patch not disabling compresion on l2arc?
>
>
> Steven Hartland wrote:
> SH> I would have expected zero for all l2_compress values.
> SH>
> SH> Regards
> SH> Steve
> SH>
> SH> ----- Original Message -----
> SH> From: "Vitalij Satanivskij" <satan@ukr.net>
> SH> To: "Steven Hartland" <killing@multiplay.co.uk>
> SH> Cc: "Vitalij Satanivskij" <satan@ukr.net>; "Dmitriy Makarov" <supportme@ukr.net>; <freebsd-current@freebsd.org>
> SH> Sent: Friday, October 25, 2013 8:32 AM
> SH> Subject: Re: ZFS L2ARC - incorrect size and abnormal system load on r255173
> SH>
> SH>
> SH> > Just after system reboot with this patch
> SH> >
> SH> > found
> SH> > kstat.zfs.misc.arcstats.l2_compress_successes: 6083
> SH> > kstat.zfs.misc.arcstats.l2_compress_zeros: 1
> SH> > kstat.zfs.misc.arcstats.l2_compress_failures: 296
> SH> >
> SH> > compression on test pool (where I'm test this patch) is lz4
> SH> >
> SH> > so is it ok ?
> SH> >
> SH> >
> SH> >
> SH> > Steven Hartland wrote:
> SH> > SH> If you are still seeing high load try commenting out the following
> SH> > SH> which should disable l2arc compression.
> SH> > SH> sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c
> SH> > SH> if (l2arc_compress)
> SH> > SH> hdr->b_flags |= ARC_L2COMPRESS;
> SH> > SH>
> SH> >
> SH>
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filename="zfs-l2arc-no-compress.patch"
Index: sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c=0A=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=0A=
--- sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c (revision =
256889)=0A=
+++ sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c (working copy)=0A=
@@ -3157,8 +3157,10 @@ top:=0A=
arc_access(hdr, hash_lock);=0A=
if (*arc_flags & ARC_L2CACHE)=0A=
hdr->b_flags |=3D ARC_L2CACHE;=0A=
+/*=0A=
if (*arc_flags & ARC_L2COMPRESS)=0A=
hdr->b_flags |=3D ARC_L2COMPRESS;=0A=
+*/=0A=
mutex_exit(hash_lock);=0A=
ARCSTAT_BUMP(arcstat_hits);=0A=
ARCSTAT_CONDSTAT(!(hdr->b_flags & ARC_PREFETCH),=0A=
@@ -3199,8 +3201,10 @@ top:=0A=
}=0A=
if (*arc_flags & ARC_L2CACHE)=0A=
hdr->b_flags |=3D ARC_L2CACHE;=0A=
+/*=0A=
if (*arc_flags & ARC_L2COMPRESS)=0A=
hdr->b_flags |=3D ARC_L2COMPRESS;=0A=
+*/=0A=
if (BP_GET_LEVEL(bp) > 0)=0A=
hdr->b_flags |=3D ARC_INDIRECT;=0A=
} else {=0A=
@@ -3217,8 +3221,10 @@ top:=0A=
add_reference(hdr, hash_lock, private);=0A=
if (*arc_flags & ARC_L2CACHE)=0A=
hdr->b_flags |=3D ARC_L2CACHE;=0A=
+/*=0A=
if (*arc_flags & ARC_L2COMPRESS)=0A=
hdr->b_flags |=3D ARC_L2COMPRESS;=0A=
+*/=0A=
buf =3D kmem_cache_alloc(buf_cache, KM_PUSHPAGE);=0A=
buf->b_hdr =3D hdr;=0A=
buf->b_data =3D NULL;=0A=
@@ -3791,8 +3797,10 @@ arc_write(zio_t *pio, spa_t *spa, uint64_t txg,=0A=
ASSERT(hdr->b_acb =3D=3D NULL);=0A=
if (l2arc)=0A=
hdr->b_flags |=3D ARC_L2CACHE;=0A=
+/*=0A=
if (l2arc_compress)=0A=
hdr->b_flags |=3D ARC_L2COMPRESS;=0A=
+*/=0A=
callback =3D kmem_zalloc(sizeof (arc_write_callback_t), KM_SLEEP);=0A=
callback->awcb_ready =3D ready;=0A=
callback->awcb_done =3D done;=0A=
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