From: Paolo Bonzini <pbonzini@redhat.com>
To: "Michael R. Hines" <mrhines@linux.vnet.ibm.com>
Cc: "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>
Subject: Re: [Qemu-devel] [RFC] parallelize migration_bitmap_sync()
Date: Fri, 01 Mar 2013 10:34:16 +0100 [thread overview]
Message-ID: <51307618.6010708@redhat.com> (raw)
In-Reply-To: <512FE6C3.5030409@linux.vnet.ibm.com>
Il 01/03/2013 00:22, Michael R. Hines ha scritto:te
> Hi,
>
> Currently migration_bitmap_sync() is very expensive: on the order of
> 15-20 milliseconds by my count using timestamps (for a simple 2GB ram
> virtual machine).
> Until new EPT processor versions come out in 2014, we need software
> support for cutting this time down much lower........by at least an
> order of magnitude.
>
> Would anyone be opposed to me writing a patch that creates N threads and
> dividing up the migration_bitmap_sync() function to have the dirty page
> scanning run in parallel?
Yes, that's a possibility. You can make a quick prototype using OpenMP.
But Juan is working on making the dirty bitmap really a bitmap (not a
"bytemap"). That should speed up migration_bitmap_sync by a factor of
64 (i.e. sizeof(long)*8).
Paolo
next parent reply other threads:[~2013-03-01 9:34 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <512FE6C3.5030409@linux.vnet.ibm.com>
2013-03-01 9:34 ` Paolo Bonzini [this message]
2013-03-01 19:32 ` [Qemu-devel] [RFC] parallelize migration_bitmap_sync() Michael R. Hines
2013-03-02 5:24 ` Michael R. Hines
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