From: Paolo Bonzini <pbonzini@redhat.com>
To: "Richard W.M. Jones" <rjones@redhat.com>,
Eric Sandeen <sandeen@redhat.com>
Cc: linux-ext4@vger.kernel.org
Subject: Re: fstrim has no effect on a just-mounted filesystem
Date: Wed, 12 Mar 2014 19:10:42 +0100 [thread overview]
Message-ID: <5320A322.7020009@redhat.com> (raw)
In-Reply-To: <20140312100507.GA19635@redhat.com>
Il 12/03/2014 11:17, Richard W.M. Jones ha scritto:
> Somewhere, the discard requests are disappearing in the stack (or more
> likely, being delayed). blktrace/trace-cmd somehow forces them out.
> But fsync/sync/umount/sleep does not. They might be stuck in qemu too ...
No, this I can be quite sure about. QEMU sends them as soon as they are
received in the SCSI layer. If they were ill-formed, QEMU would fail
them. If they got stuck, sooner or later you'd not be able to do I/O
anymore (there is a queue depth limit) and the guest would start getting
timeouts.
Also, certainly blktrace would have no effect on QEMU.
Paolo
next prev parent reply other threads:[~2014-03-12 18:10 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-03-11 21:39 fstrim has no effect on a just-mounted filesystem Richard W.M. Jones
2014-03-11 21:47 ` Eric Sandeen
2014-03-11 22:00 ` Richard W.M. Jones
2014-03-11 22:04 ` Richard W.M. Jones
2014-03-11 22:08 ` Eric Sandeen
2014-03-11 22:59 ` Richard W.M. Jones
2014-03-11 23:07 ` Richard W.M. Jones
2014-03-11 23:09 ` Eric Sandeen
2014-03-11 23:30 ` Richard W.M. Jones
2014-03-12 10:17 ` Richard W.M. Jones
2014-03-12 13:42 ` Richard W.M. Jones
2014-03-12 18:10 ` Paolo Bonzini [this message]
2014-03-12 18:24 ` Richard W.M. Jones
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