[illumos-Advocates] RTI (taskq changes)

[Garrett D'Amore]

This fixes two outstanding issues:

garrett at thinkpad{9}> hg outgoing -v
running ssh anonhg at hg.illumos.org "hg -R illumos-gate serve --stdio"
remote: Not trusting file /export/illumos/hgrepos/illumos-gate/.hg/hgrc
from untrusted user hg, group hg
comparing with ssh://anonhg@hg.illumos.org/illumos-gate
searching for changes

changeset:   13389:f3f43b6a5505
tag:         tip
user:        Garrett D'Amore <garrett at nexenta.com>
date:        Wed Jul 06 16:14:21 2011 -0700

description:
	734 taskq_dispatch_prealloc() desired
	943 zio_interrupt ends up calling taskq_dispatch with TQ_SLEEP
	Reviewed by: Albert Lee <trisk at nexenta.com>
	Reviewed by: Richard Lowe <richlowe at richlowe.net>
	Reviewed by: Alexey Zaytsev <alexey.zaytsev at nexenta.com>
	Reviewed by: Jason Brian King <jason.brian.king at gmail.com>

modified:
   usr/src/uts/common/fs/zfs/sys/zio.h
   usr/src/uts/common/fs/zfs/zio.c
   usr/src/uts/common/os/taskq.c
   usr/src/uts/common/sys/taskq_impl.h


garrett at thinkpad{20}> hg pbchk
remote: Not trusting file /export/illumos/hgrepos/illumos-gate/.hg/hgrc
from untrusted user hg, group hg
remote: Not trusting file /export/illumos/hgrepos/illumos-gate/.hg/hgrc
from untrusted user hg, group hg
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We have tested these changes in Nexenta, and they will be going into our
product.  The performance improvement is modest for some cases, more
severe when memory utilization is high.  There will be a forthcoming
change in the COMSTAR that addresses a problem with iSCSI session drops,
and this patch is a prerequisite.  (Basically another sleeping
taskq_dispatch where there shouldn't be one...)

Conceptually, these changes have been reviewed by members of the ZFS
working group, as well as a few other individuals.

Nightly build mail pasted below.  

garrett at thinkpad{17}> cat log/log.2011-06-22.21:43/mail_msg

==== Nightly distributed build started:   Wed Jun 22 19:40:32 PDT 2011
====
==== Nightly distributed build completed: Wed Jun 22 21:43:22 PDT 2011
====

==== Total build time ====

real    2:02:50

==== Build environment ====

/usr/bin/uname
SunOS thinkpad 5.11 1880 i86pc i386 i86pc

/opt/SUNWspro/bin/dmake
dmake: Sun Distributed Make 7.8 SunOS_i386 Patch 126504-01 2007/07/19
number of concurrent jobs = 10

32-bit compiler
/opt/onbld/bin/i386/cw -_cc
cw version 1.29
primary: /opt/SUNWspro/bin/cc
cc: Sun C 5.9 SunOS_i386 Patch 124868-10 2009/04/30
shadow: /usr/sfw/bin/gcc
gcc (GCC) 3.4.3 (csl-sol210-3_4-20050802)

64-bit compiler
/opt/onbld/bin/i386/cw -_cc
cw version 1.29
primary: /opt/SUNWspro/bin/cc
cc: Sun C 5.9 SunOS_i386 Patch 124868-10 2009/04/30
shadow: /usr/sfw/bin/gcc
gcc (GCC) 3.4.3 (csl-sol210-3_4-20050802)

/usr/java/bin/javac
java full version "1.6.0_21-b06"

/usr/ccs/bin/as
as: Sun Compiler Common 12 SunOS_i386 snv_121 08/03/2009

/usr/ccs/bin/ld
ld: Software Generation Utilities - Solaris Link Editors: 5.11-1.1726

Build project:  group.staff
Build taskid:   131

==== Nightly argument issues ====


==== Build version ====

taskq

==== Make clobber ERRORS ====


==== Make tools clobber ERRORS ====


==== Tools build errors ====


==== Build errors (DEBUG) ====


==== Build warnings (DEBUG) ====


==== Elapsed build time (DEBUG) ====

real  1:16:02.1
user  6:40:47.9
sys   1:25:46.2

==== Build noise differences (DEBUG) ====


==== package build errors (DEBUG) ====


==== Validating manifests against proto area ====


==== Check ELF runtime attributes ====


==== Diff ELF runtime attributes (since last build) ====


==== 'dmake lint' of src ERRORS ====


==== Elapsed time of 'dmake lint' of src ====

real    29:12.6
user  1:36:55.1
sys     30:15.3

==== lint warnings src ====


==== lint noise differences src ====


==== cstyle/hdrchk errors ====


==== Find core files ====


==== Check lists of files ====


==== Impact on file permissions ====