From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45463) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YzNkL-0005ZN-0z for qemu-devel@nongnu.org; Mon, 01 Jun 2015 07:19:09 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YzNkK-0000hD-05 for qemu-devel@nongnu.org; Mon, 01 Jun 2015 07:19:08 -0400 Sender: Dmitry Monakhov From: Dmitry Monakhov In-Reply-To: <556C36BC.1000409@redhat.com> References: <1430746944-27347-1-git-send-email-den@openvz.org> <20150511150817.GK16270@stefanha-thinkpad.redhat.com> <5550D3B5.2050703@openvz.org> <5550DD2D.8000407@odin.com> <20150512100155.GB11497@stefanha-thinkpad.redhat.com> <5551D39E.1020902@odin.com> <5551DA21.7020105@redhat.com> <20150513154342.GB24352@stefanha-thinkpad.redhat.com> <55538001.90207@odin.com> <5568974C.6080502@redhat.com> <877frn90pz.fsf@openvz.org> <556C36BC.1000409@redhat.com> Date: Mon, 01 Jun 2015 14:16:32 +0300 Message-ID: <87382b8yr3.fsf@openvz.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH v5 0/2] block: enforce minimal 4096 alignment in qemu_blockalign List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini , "Denis V. Lunev" , Stefan Hajnoczi Cc: Dmitry Monakhov , Stefan Hajnoczi , qemu-block@nongnu.org, qemu-devel@nongnu.org Paolo Bonzini writes: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA256 > > > > On 01/06/2015 12:34, Dmitry Monakhov wrote: >> Yes. Improvement is not huge, but it can be detected for old qemu=20 >> unpatched kernel: 728 MiB/sec =C2=B1 20Mb patched kernel : 748 MiB/sec >> =C2=B1 10Mb > > Ok, so about 3-4%. What does the blktrace look like with a patched > kernel, and what is the performance with old QEMU? new qemu looks perfect 259,0 31 62 0.711100207 10768 D WS 29364992 + 256 [qemu-io] 259,0 31 63 0.711128098 10768 Q WS 29365248 + 256 [qemu-io] 259,0 31 64 0.711128509 10768 G WS 29365248 + 256 [qemu-io] 259,0 31 65 0.711130463 10768 D WS 29365248 + 256 [qemu-io] 259,0 31 66 0.711134222 10768 C WS 29364480 + 256 [0] 259,0 31 67 0.711158858 10768 Q WS 29365504 + 256 [qemu-io] 259,0 31 68 0.711159226 10768 G WS 29365504 + 256 [qemu-io] 259,0 31 69 0.711161104 10768 D WS 29365504 + 256 [qemu-io] 259,0 31 70 0.711171863 10768 C WS 29364736 + 256 [0] old qemu on patched kernel stil issues two bios Max_sz-1page + 1page, such = bios are not merged and completed separately=20=20 259,0 31 385 0.719283423 10729 Q WS 29376775 + 248 [qemu-io] 259,0 31 386 0.719283694 10729 G WS 29376775 + 248 [qemu-io] 259,0 31 387 0.719285909 10729 D WS 29376775 + 248 [qemu-io] 259,0 31 388 0.719287600 10729 Q WS 29377023 + 8 [qemu-io] 259,0 31 389 0.719287810 10729 G WS 29377023 + 8 [qemu-io] 259,0 31 390 0.719288666 10729 D WS 29377023 + 8 [qemu-io] 259,0 31 391 0.719315193 10729 Q WS 29377031 + 248 [qemu-io] 259,0 31 392 0.719315400 10729 G WS 29377031 + 248 [qemu-io] 259,0 31 393 0.719317411 10729 D WS 29377031 + 248 [qemu-io] 259,0 31 394 0.719319179 10729 Q WS 29377279 + 8 [qemu-io] 259,0 31 395 0.719319366 10729 G WS 29377279 + 8 [qemu-io] 259,0 31 396 0.719320014 10729 D WS 29377279 + 8 [qemu-io] ..... 259,0 31 916 0.722132787 10729 C WS 29377031 + 248 [0] .... 259,0 31 995 0.722549469 10729 C WS 29376775 + 248 [0] .... 259,0 31 4260 0.748148953 10729 C WS 29377023 + 8 [0] ..... 259,0 31 4274 0.748217568 10729 C WS 29377279 + 8 [0] I'm not quite sure why each bio dispatched to device that soon, AFAIU plug/= unplug scope whole do_direct_IO() loop, So bio it looks like bio submit to request path should be modified. > > Paolo > >> IMHO patch is not sufficient. We have to correct bio construction >> inside direct-io code. I'll be back with the patch.