From: Fam Zheng <famz@redhat.com>
To: Bob Chen <a175818323@gmail.com>
Cc: qemu-block@nongnu.org, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] QEMU 1.1.2: block IO throttle might occasionally freeze running process's IO to zero
Date: Thu, 1 Dec 2016 17:52:07 +0800 [thread overview]
Message-ID: <20161201095207.GB28711@lemon> (raw)
In-Reply-To: <CAMxP3BQptSjDJCoakSjT4CU-034rj4hgQ5JoQsoxMCk-3sQpKw@mail.gmail.com>
On Thu, 12/01 12:07, Bob Chen wrote:
> Test case:
>
> 1. QEMU 1.1.2
> 2. Run fio inside the vm, give it some pressure. Watch the realtime
> throughput
> 3. block_set_io_throttle drive_2 100000000 0 0 2000 0 0 # throttle
> bps and iops, any value
> 4. Observed that the IO is very likely to freeze to zero. The fio process
> stuck!
> 5. Kill the former fio process, start a new one. The IO turns back to normal
>
> Didn't reproduce it with QEMU 2.5.
>
>
> Actually I'm not wishfully thinking the community would help fix this bug
> on such an ancient version. Just hope someone can tell me what is the root
> cause. Then I have to evaluate whether I should move to higher version
> QEMU, or fix this bug on 1.1.2 in-place(if it is a small one).
The throttling implementation is completely refreshed so I think it's not easy
to suggest a root cause for you.
Fam
next prev parent reply other threads:[~2016-12-01 9:52 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-01 4:07 [Qemu-devel] QEMU 1.1.2: block IO throttle might occasionally freeze running process's IO to zero Bob Chen
2016-12-01 9:52 ` Fam Zheng [this message]
2016-12-01 10:16 ` Paolo Bonzini
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