From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:47863) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1f3dQv-0000Au-5i for qemu-devel@nongnu.org; Wed, 04 Apr 2018 04:06:21 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1f3dQr-0000Uk-1B for qemu-devel@nongnu.org; Wed, 04 Apr 2018 04:06:17 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:52462 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1f3dQq-0000UI-T2 for qemu-devel@nongnu.org; Wed, 04 Apr 2018 04:06:12 -0400 Date: Wed, 4 Apr 2018 16:06:00 +0800 From: Peter Xu Message-ID: <20180404080600.GA10540@xz-mi> References: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Subject: Re: [Qemu-devel] [PATCH] migration: calculate expected_downtime with ram_bytes_remaining() List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Balamuruhan S , "Dr. David Alan Gilbert" Cc: qemu-devel@nongnu.org, amit.shah@redhat.com, quintela@redhat.com On Wed, Apr 04, 2018 at 11:55:14AM +0530, Balamuruhan S wrote: [...] > > too. So still I'll put aside the "which one is better" question. > > > > For your use case, you can have a look on either of below way to > > have a converged migration: > > > > - auto-converge: that's a migration capability that throttles CPU > > usage of guests > > I used auto-converge option before hand and still it doesn't help > for migration to complete Have you digged about why? AFAIK auto-convergence will at last absort merely the whole vcpu resource (99% of them maximum). Maybe you are not with the best throttle values? Or do you think that could be a auto-convergence bug too? > > > > > - postcopy: that'll let you start the destination VM even without > > transferring all the RAMs before hand > > I am seeing issue in postcopy migration between POWER8(16M) -> POWER9(1G) > where the hugepage size is different. I am trying to enable it but host > start > address have to be aligned with 1G page size in ram_block_discard_range(), > which I am debugging further to fix it. I thought the huge page size needs to be matched on both side currently for postcopy but I'm not sure. CC Dave (though I think Dave's still on PTO). -- Peter Xu