From: Vladimir Sementsov-Ogievskiy <vsementsov@parallels.com>
To: famz@redhat.com
Cc: Kevin Wolf <kwolf@redhat.com>, Benoit Canet <benoit@irqsave.net>,
John Snow <jsnow@redhat.com>,
Markus Armbruster <armbru@redhat.com>,
qemu-devel@nongnu.org, Max Reitz <mreitz@redhat.com>,
Stefan Hajnoczi <stefanha@redhat.com>,
Jd <jd_jedi@convirture.com>, Paolo Bonzini <pbonzini@redhat.com>,
Luiz Capitulino <lcapitulino@redhat.com>
Subject: Re: [Qemu-devel] [PATCH v6 07/10] qmp: Add support of "dirty-bitmap" sync mode for drive-backup
Date: Wed, 12 Nov 2014 14:23:35 +0300 [thread overview]
Message-ID: <54634337.9030707@parallels.com> (raw)
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> @@ -317,7 +321,21 @@ static void coroutine_fn backup_run(void *opaque)
> if (alloced == 0) {
> continue;
> }
> + } else if (job->sync_mode == MIRROR_SYNC_MODE_DIRTY_BITMAP) {
> + int i, dirty = 0;
> + for (i = 0; i < BACKUP_SECTORS_PER_CLUSTER;
> + i += job->sync_bitmap_gran) {
> + if (bdrv_get_dirty(bs, job->sync_bitmap,
> + start * BACKUP_SECTORS_PER_CLUSTER + i)) {
> + dirty = 1;
> + break;
> + }
> + }
> + if (!dirty) {
> + continue;
> + }
> }
> +
With such solution we don't use the power of HBitmap, which provides
"hbitmap_iter_skip_words", with O(log(n)) complexity. Here we look
through the whole bitmap (O(n)), instead of jumping to the next dirty bit.
--
С уважением,
Владимир
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next reply other threads:[~2014-11-12 11:24 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-12 11:23 Vladimir Sementsov-Ogievskiy [this message]
-- strict thread matches above, loose matches on Subject: below --
2014-10-30 3:22 [Qemu-devel] [PATCH v6 00/10] block: Incremental backup series Fam Zheng
2014-10-30 3:22 ` [Qemu-devel] [PATCH v6 07/10] qmp: Add support of "dirty-bitmap" sync mode for drive-backup Fam Zheng
2014-11-04 10:53 ` Max Reitz
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