* Re: [Qemu-devel] [libvirt] speeding up qemu core dumps
[not found] ` <4E3960EF.60603@redhat.com>
@ 2011-08-04 3:42 ` Jim Fehlig
2011-08-04 8:07 ` Daniel P. Berrange
0 siblings, 1 reply; 2+ messages in thread
From: Jim Fehlig @ 2011-08-04 3:42 UTC (permalink / raw)
To: Eric Blake; +Cc: LibVir, qemu-devel
Eric Blake wrote:
> On 08/03/2011 08:37 AM, Jim Fehlig wrote:
>> http://lists.nongnu.org/archive/html/qemu-devel/2011-02/msg01156.html
>>
>> I thought there were more discussions on the topic but can only find the
>> above thread ATM.
>>
>> Do folks here have objections to increasing the migration speed prior to
>> core dump? If not, any suggestions for a value? I set the migration
>> speed to 1G in doCoreDump() prior to calling qemuMigrationToFile() with
>> following improvement dumping a 4G guest
>
> Why any limit at all? When dumping to file rather than network, I
> can't think of any justification for a default limit when targetting a
> local drive (a particular installation may have a reasonable limit,
> especially if the file involved happens to use a network - think
> NFS). It seems like it would make sense to override the qemu defaults
> and go with unlimited speed for faster dump and save operations.
Agreed, 1G was just a test value, but I'm haven't yet figured out how to
define unlimited. From libvirt json monitor connection I tried
migrate_set_speed with INT64_MAX, but that was invalid. Using qemu
monitor directly, I can go as high as INT64_MAX-512
(qemu) migrate_set_speed 9223372036854775295B
(qemu) migrate_set_speed 9223372036854775296B
invalid size
Any hints on proper way to set unlimited migration speed?
Regards,
Jim
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [Qemu-devel] [libvirt] speeding up qemu core dumps
2011-08-04 3:42 ` [Qemu-devel] [libvirt] speeding up qemu core dumps Jim Fehlig
@ 2011-08-04 8:07 ` Daniel P. Berrange
0 siblings, 0 replies; 2+ messages in thread
From: Daniel P. Berrange @ 2011-08-04 8:07 UTC (permalink / raw)
To: Jim Fehlig; +Cc: LibVir, Eric Blake, qemu-devel
On Wed, Aug 03, 2011 at 09:42:23PM -0600, Jim Fehlig wrote:
> Eric Blake wrote:
> > On 08/03/2011 08:37 AM, Jim Fehlig wrote:
> >> http://lists.nongnu.org/archive/html/qemu-devel/2011-02/msg01156.html
> >>
> >> I thought there were more discussions on the topic but can only find the
> >> above thread ATM.
> >>
> >> Do folks here have objections to increasing the migration speed prior to
> >> core dump? If not, any suggestions for a value? I set the migration
> >> speed to 1G in doCoreDump() prior to calling qemuMigrationToFile() with
> >> following improvement dumping a 4G guest
> >
> > Why any limit at all? When dumping to file rather than network, I
> > can't think of any justification for a default limit when targetting a
> > local drive (a particular installation may have a reasonable limit,
> > especially if the file involved happens to use a network - think
> > NFS). It seems like it would make sense to override the qemu defaults
> > and go with unlimited speed for faster dump and save operations.
>
> Agreed, 1G was just a test value, but I'm haven't yet figured out how to
> define unlimited. From libvirt json monitor connection I tried
> migrate_set_speed with INT64_MAX, but that was invalid. Using qemu
> monitor directly, I can go as high as INT64_MAX-512
>
> (qemu) migrate_set_speed 9223372036854775295B
> (qemu) migrate_set_speed 9223372036854775296B
> invalid size
>
> Any hints on proper way to set unlimited migration speed?
The code doesn't seem to have a way to set a truely unlimited rate,
but even INT64_MAX / 2 would be more than sufficient for us to max
out the host OS storage throughput
Daniel
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^ permalink raw reply [flat|nested] 2+ messages in thread
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[not found] ` <4E3960EF.60603@redhat.com>
2011-08-04 3:42 ` [Qemu-devel] [libvirt] speeding up qemu core dumps Jim Fehlig
2011-08-04 8:07 ` Daniel P. Berrange
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