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From: Paolo Bonzini <pbonzini@redhat.com>
To: Kevin Wolf <kwolf@redhat.com>
Cc: "nbd-general@lists.sourceforge.net"
	<nbd-general@lists.sourceforge.net>,
	"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>,
	Alex Bligh <alex@alex.org.uk>
Subject: Re: [Qemu-devel] [Nbd] Is NBD_CMD_FLAG_FUA valid during NBD_CMD_FLUSH?
Date: Tue, 5 Apr 2016 15:28:47 +0200	[thread overview]
Message-ID: <5703BD8F.1080409@redhat.com> (raw)
In-Reply-To: <20160405050926.GC4183@noname.redhat.com>



On 05/04/2016 07:09, Kevin Wolf wrote:
> > TRIM is an advisory operation, so it doesn't make sense to force access
> > to the medium.
> 
> I think it does make sense. It means that on completion there is no
> pending discard operation (i.e. either there wasn't a discard or if
> there was, it has completed) and other readers will see the final state
> of the blocks.

This is what already happens though, isn't it?

Paolo

>> > The closest you could get would be to add FUA to WRITE_ZEROES.  But
>> > since WRITE_ZEROES is not a particularly common operation there isn't
>> > much to gain compared to FLUSHing after the write has completed; in
>> > fact SCSI doesn't have a FUA bit on its WRITE SAME command.
> Right, I guess this would mostly be for consistency when FUA is
> supported more or less everywhere else.

  reply	other threads:[~2016-04-05 13:28 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-03-31 19:33 [Qemu-devel] Is NBD_CMD_FLAG_FUA valid during NBD_CMD_FLUSH? Eric Blake
2016-03-31 19:41 ` [Qemu-devel] [Nbd] " Alex Bligh
2016-03-31 19:54   ` Eric Blake
2016-03-31 20:17     ` Alex Bligh
2016-03-31 20:34       ` Eric Blake
2016-04-01  7:49         ` Paolo Bonzini
2016-04-01  9:25           ` Alex Bligh
2016-04-01  8:27         ` Wouter Verhelst
2016-04-01  9:40           ` Alex Bligh
2016-04-01 14:16           ` Eric Blake
2016-04-01 15:00             ` Alex Bligh
2016-04-01 15:08               ` Eric Blake
2016-04-01 15:12                 ` Alex Bligh
2016-04-01 15:13                   ` Alex Bligh
2016-04-01 15:31                     ` Eric Blake
2016-04-01 15:46                       ` Alex Bligh
2016-05-02 17:08         ` Eric Blake
2016-04-01  7:43       ` Paolo Bonzini
2016-04-01  9:19         ` Alex Bligh
2016-04-05  5:09         ` Kevin Wolf
2016-04-05 13:28           ` Paolo Bonzini [this message]
2016-04-06 13:14             ` Kevin Wolf
2016-04-06 13:28               ` Paolo Bonzini
2016-04-06 13:50                 ` Kevin Wolf

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