From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43768) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cty0w-0005Wr-6e for qemu-devel@nongnu.org; Fri, 31 Mar 2017 10:58:59 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cty0t-0007tH-5m for qemu-devel@nongnu.org; Fri, 31 Mar 2017 10:58:58 -0400 Received: from mx1.redhat.com ([209.132.183.28]:46886) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cty0s-0007sQ-TX for qemu-devel@nongnu.org; Fri, 31 Mar 2017 10:58:55 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id A6A997AEA4 for ; Fri, 31 Mar 2017 14:58:53 +0000 (UTC) Date: Fri, 31 Mar 2017 15:58:45 +0100 From: "Dr. David Alan Gilbert" Message-ID: <20170331145844.GL4514@work-vm> References: <20170323204544.12015-1-quintela@redhat.com> <20170323204544.12015-12-quintela@redhat.com> <20170327092350.GH11497@pxdev.xzpeter.org> <8737dxqm1y.fsf@secure.mitica> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8737dxqm1y.fsf@secure.mitica> Subject: Re: [Qemu-devel] [PATCH 11/51] ram: Move dup_pages into RAMState List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Juan Quintela Cc: Peter Xu , qemu-devel@nongnu.org * Juan Quintela (quintela@redhat.com) wrote: > Peter Xu wrote: > > On Thu, Mar 23, 2017 at 09:45:04PM +0100, Juan Quintela wrote: > >> Once there rename it to its actual meaning, zero_pages. > >> > >> Signed-off-by: Juan Quintela > >> Reviewed-by: Dr. David Alan Gilbert > > > > Reviewed-by: Peter Xu > > > > Will post a question below though (not directly related to this patch > > but context-wide)... > >> { > >> int pages = -1; > >> > >> if (is_zero_range(p, TARGET_PAGE_SIZE)) { > >> - acct_info.dup_pages++; > >> + rs->zero_pages++; > >> *bytes_transferred += save_page_header(f, block, > >> offset | RAM_SAVE_FLAG_COMPRESS); > >> qemu_put_byte(f, 0); > >> @@ -822,11 +826,11 @@ static int ram_save_page(RAMState *rs, MigrationState *ms, QEMUFile *f, > >> if (bytes_xmit > 0) { > >> acct_info.norm_pages++; > >> } else if (bytes_xmit == 0) { > >> - acct_info.dup_pages++; > >> + rs->zero_pages++; > > > > This code path looks suspicous... since iiuc currently it should only > > be triggered by RDMA case, and I believe here qemu_rdma_save_page() > > should have met something wrong (so that it didn't return with > > RAM_SAVE_CONTROL_DELAYED). Then is it correct we do increase zero page > > counting unconditionally here? (hmm, the default bytes_xmit is zero as > > well...) > > My head hurts at this point. > ok. bytse_xmit can only be zero if we called qemu_rdma_save_page() with > size=0 or there has been an RDMA error. We ver call the function with > size = 0. And if there is one error, we are in very bady shape already. > > > Another thing is that I see when RDMA is enabled we are updating > > accounting info with acct_update_position(), while we updated it here > > as well. Is this an issue of duplicated accounting? > > I think stats and rdma are not right. I have to check more that. It should be vaguely right; the rdma code calls back into acct_update_position to update them; but I agree it looks odd; that line almost looks like it's the error case - so why is it incrementing dup_pages? Dave > Thanks, Juan. -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK