Some guests (win2008 server for example) do a lot of unnecessary
flushing when underlying media has not changed. This adds additional
overhead on host when calling fsync/fdatasync.
This change introduces a write generation scheme in BlockDriverState.
Current write generation is checked against last flushed generation to
avoid unnessesary flushes.
The problem with excessive flushing was found by a performance test
which does parallel directory tree creation (from 2 processes).
Results improved from 0.424 loops/sec to 0.432 loops/sec.
Each loop creates 10^3 directories with 10 files in each.
This affected some blkdebug testcases that were expecting error logs from
failure-injected flushes which are now skipped entirely
(tests 026 071 089).
This also affects the performance of block jobs and thus BLOCK_JOB_READY
events for driver-mirror and active block-commit commands now arrives
faster, before QMP send successfully returns to caller (tests 141 144).
Signed-off-by: Evgeny Yakovlev <eyakovlev@virtuozzo.com>
Signed-off-by: Denis V. Lunev <den@openvz.org>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 1468870792-7411-5-git-send-email-den@openvz.org
CC: Kevin Wolf <kwolf@redhat.com>
CC: Max Reitz <mreitz@redhat.com>
CC: Stefan Hajnoczi <stefanha@redhat.com>
CC: Fam Zheng <famz@redhat.com>
CC: John Snow <jsnow@redhat.com>
Signed-off-by: John Snow <jsnow@redhat.com>
This patch fixes longstanding issue with 026 iotest. Unfortunately,
this test contains 2 versions of the correct output, one for cached
writes and one for non-cached ones. People tends to fix only one
version of output of the test and thus noncached version becomes
broken. Unfortunately, it is default in tests/check-block.sh
The following problematic commits were made:
commit 3b5e14c76a
Author: Max Reitz <mreitz@redhat.com>
Date: Tue Dec 2 18:32:51 2014 +0100
qcow2: Flushing the caches in qcow2_close may fail
commit a069e2f137
Author: John Snow <jsnow@redhat.com>
Date: Fri Feb 6 16:26:17 2015 -0500
blkdebug: fix "once" rule
commit b106ad9185
Author: Kevin Wolf <kwolf@redhat.com>
Date: Fri Mar 28 18:06:31 2014 +0100
qcow2: Don't rely on free_cluster_index in alloc_refcount_block()
Signed-off-by: Pavel Butsykin <pbutsykin@virtuozzo.com>
Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Max Reitz <mreitz@redhat.com>
CC: John Snow <jsnow@redhat.com>
CC: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Our qapi conventions document that '.' should only be used in
the prefix of downstream names. BlkdebugEvent was a lone
exception to this. Changing this is not backwards compatible
to the 'blockdev-add' QMP command; however, that command is
not yet fully stable. It can also be argued that the testsuite
is the biggest user of blkdebug, and that any other user can
be taught to deal with the change by paying attention to
introspection results.
Done with:
$ for str in \
l1_grow.{alloc,write,activate}_table \
l2_alloc.{cow_read,write} \
refblock_alloc.{hookup,write,write_blocks,write_table,switch_table} \
pwritev_rmw.{head,after_head,tail,after_tail}; do
str1=$(echo "$str" | sed 's/\./\\./')
str2=$(echo "$str" | sed 's/\./_/')
git grep -l "$str1" | xargs -r sed -i "s/$str1/$str2/g"
done
followed by a manual touchup to test 77 to keep the test working.
Reported-by: Markus Armbruster <armbru@redhat.com>
CC: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <1447836791-369-21-git-send-email-eblake@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Because l2_allocate now frees the unused L2 cluster on error, the
according test cases in 026 don't result in one leaked cluster anymore.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
The reference output for test case 026 hasn't been updated in a long
time and it's one of the "known failing" cases. This patch updates the
reference output so that unintentional changes can be reliably detected
again.
The problem with this test case is that it produces different output
depending on whether -nocache is used or not. The solution of this patch
is to actually have two different reference outputs. If nnn.out.nocache
exists, it is used as the reference output for -nocache; otherwise,
nnn.out stays valid for both cases.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
