qemu-devel@nongnu.org
[Top] [All Lists]

Re: [kvm-devel] [Qemu-devel] [PATCH] QEMU: fsync AIO writes on flush req

Subject: Re: [kvm-devel] [Qemu-devel] [PATCH] QEMU: fsync AIO writes on flush request
From: Paul Brook
Date: Sat, 29 Mar 2008 02:02:53 +0000
> That'll depend on what kind of device is emulated.  Does the SCSI
> emulation handle multiple in-flight commands with any guarantee on
> order?

SCSI definitely allows (and we emulate) multiple in flight commands.
I can't find any requirement that writes must complete before a subsequent 
SYNCHRONISE_CACHE. However I don't claim to know the spec that well, and it's 
probably not a bad idea have them complete anyway. Preferably this would be a 
completely asynchronous operation. i.e. the sync command returns immediately, 
but only completes when all preceding writes have completed and been flushed 
to disk.

Paul


<Prev in Thread] Current Thread [Next in Thread>