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From: Paolo Bonzini <pbonzini@redhat.com>
To: Liang Li <liang.z.li@intel.com>, qemu-devel@nongnu.org
Cc: amit.shah@redhat.com, Wanpeng Li <wanpeng.li@linux.intel.com>,
	yong.y.wang@intel.com, stefanha@redhat.com, quintela@redhat.com
Subject: Re: [Qemu-devel] [v2 RESEND 0/4] Fix long vm downtime during live migration
Date: Mon, 2 Nov 2015 12:54:57 +0100	[thread overview]
Message-ID: <56374F11.30309@redhat.com> (raw)
In-Reply-To: <1446449823-25049-1-git-send-email-liang.z.li@intel.com>



On 02/11/2015 08:36, Liang Li wrote:
> The patch 3ea3b7fa9af067982f34b of kvm introduces a lazy collapsing
> of small sptes into large sptes mechanism, which intend to solve the
> performance drop issue if live migration fails or is canceled. The
> rmap will be scanned in the KVM_SET_USER_MEMORY_REGION ioctl context
> when dirty logging is stopped so as to drop the small sptes, scanning
> the rmap and drop the small sptes is a time consuming operation which
> will take dozens of milliseconds, the actual time depends on VM's
> memory size. For a VM with 8GB RAM, it will take about 30ms.

I'm okay with these patches.  Juan, can they be included in 2.5?

However, the KVM patch is a regression too.  Wanpeng, can you look into
doing the collapsing from a work item?

Thanks,

Paolo

  parent reply	other threads:[~2015-11-02 11:55 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-11-02  7:36 [Qemu-devel] [v2 RESEND 0/4] Fix long vm downtime during live migration Liang Li
2015-11-02  7:37 ` [Qemu-devel] [v2 RESEND 1/4] migration: defer migration_end & blk_mig_cleanup Liang Li
2015-11-03 12:28   ` Juan Quintela
2015-11-02  7:37 ` [Qemu-devel] [v2 RESEND 2/4] migration: rename qemu_savevm_state_cancel Liang Li
2015-11-03 12:29   ` Juan Quintela
2015-11-02  7:37 ` [Qemu-devel] [v2 RESEND 3/4] migration: rename cancel to cleanup in SaveVMHandles Liang Li
2015-11-03 12:30   ` Juan Quintela
2015-11-02  7:37 ` [Qemu-devel] [v2 RESEND 4/4] migration: code clean up Liang Li
2015-11-03 12:30   ` Juan Quintela
2015-11-02 11:54 ` Paolo Bonzini [this message]
2015-11-03 12:36   ` [Qemu-devel] [v2 RESEND 0/4] Fix long vm downtime during live migration Juan Quintela
2015-11-02 14:40 ` Stefan Hajnoczi
2015-11-03 12:23 ` Amit Shah

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