From: Fam Zheng <famz@redhat.com>
To: 858585 jemmy <jemmy858585@gmail.com>
Cc: Stefan Hajnoczi <stefanha@gmail.com>,
qemu block <qemu-block@nongnu.org>,
Juan Quintela <quintela@redhat.com>,
Dave Gilbert <dgilbert@redhat.com>,
qemu-devel <qemu-devel@nongnu.org>,
Stefan Hajnoczi <stefanha@redhat.com>,
Lidong Chen <lidongchen@tencent.com>
Subject: Re: [Qemu-devel] [Qemu-block] [PATCH v6] migration/block: use blk_pwrite_zeroes for each zero cluster
Date: Mon, 17 Apr 2017 11:47:44 +0800 [thread overview]
Message-ID: <20170417034744.GB6717@lemon.lan> (raw)
In-Reply-To: <CAOGPPbeKhfPg92GZ+rNmZdz6G59HK+pJFTrps7Nc0x1O41oGTQ@mail.gmail.com>
On Fri, 04/14 14:48, 858585 jemmy wrote:
> >> Effectively, if no cluster is zero, this patch still splits a big write into
> >> small ones, which is the opposition of usual performance optimizations (i.e.
> >> trying to coalesce requests).
> >
> > Good point!
> >
> > Another patch can modify the loop to perform the largest writes
> > possible. In other words, do not perform the write immediately and
> > keep a cluster counter instead. When the zero/non-zero state changes,
> > perform the write for the accumulated cluster count.
>
> if the zero/non-zero state changes very frequently, it will not work.
It will work, but just not improving anything. I think this is a worthwhile
optimzation to do.
Fam
prev parent reply other threads:[~2017-04-17 3:47 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-13 2:34 [Qemu-devel] [PATCH v6] migration/block: use blk_pwrite_zeroes for each zero cluster jemmy858585
2017-04-13 14:16 ` Stefan Hajnoczi
2017-04-14 0:57 ` 858585 jemmy
2017-04-14 6:00 ` Fam Zheng
2017-04-14 6:30 ` 858585 jemmy
2017-04-17 3:49 ` Fam Zheng
2017-04-17 4:00 ` 858585 jemmy
2017-04-24 7:40 ` 858585 jemmy
2017-04-24 11:54 ` 858585 jemmy
2017-04-24 12:09 ` Fam Zheng
2017-04-24 12:15 ` 858585 jemmy
2017-04-24 12:19 ` Fam Zheng
2017-04-24 12:26 ` 858585 jemmy
2017-04-24 12:36 ` Fam Zheng
2017-04-24 12:44 ` 858585 jemmy
2017-04-14 6:38 ` [Qemu-devel] [Qemu-block] " Stefan Hajnoczi
2017-04-14 6:48 ` 858585 jemmy
2017-04-17 3:47 ` Fam Zheng [this message]
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