From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:57710) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fLqrW-0007SH-5T for qemu-devel@nongnu.org; Thu, 24 May 2018 10:05:03 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fLqrQ-0000fr-FV for qemu-devel@nongnu.org; Thu, 24 May 2018 10:05:02 -0400 Date: Thu, 24 May 2018 15:04:53 +0100 From: Stefan Hajnoczi Message-ID: <20180524140453.GB28984@stefanha-x1.localdomain> References: <42ec7519-653d-09e2-abc6-78f04733ca47@linux.ibm.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="mojUlQ0s9EVzWg2t" Content-Disposition: inline In-Reply-To: <42ec7519-653d-09e2-abc6-78f04733ca47@linux.ibm.com> Subject: Re: [Qemu-devel] [Qemu-block] Problem with data miscompare using scsi-hd, cache=none and io=threads List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Daniel Henrique Barboza Cc: "qemu-devel@nongnu.org" , qemu-block@nongnu.org, Kevin Wolf , Paolo Bonzini , Fam Zheng --mojUlQ0s9EVzWg2t Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, May 15, 2018 at 06:25:46PM -0300, Daniel Henrique Barboza wrote: > This means that the test executed a write at=A0 LBA 0x94fa and, after > confirming that the write was completed, issue 2 reads in the same LBA to > assert the written contents and found out a mismatch. Have you confirmed this pattern at various levels in the stack: 1. Application inside the guest (strace) 2. Guest kernel block layer (blktrace) 3. QEMU (strace) 4. Host kernel block layer (blktrace) The key thing is that the write completes before the 2 reads are submitted. Have you tried running the test on bare metal? Stefan --mojUlQ0s9EVzWg2t Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEcBAEBAgAGBQJbBsaFAAoJEJykq7OBq3PI3OkIAMIVtABzSHMf2gJ8abYDStIk NCmbjfN5cV++Xptc94inBD8l/4rvEsIytvDY17WCTvOp8kqvPKBBm3QbSnAX3GmG CiSGG5VGbAPO+OkmqHZwrzEdfPjfl1nd/4SGv5To8xo5uxRLAXWIFynw/jxhoR8X GIZn7VsI3+V1lc2fLPJOxj16Q5RQkBpAcdAOGfFmE2FyqICjASIarBifP8qHWdcr txdtKmWO70dhbkBc6qHcEX8PR2AHBnwrqijcK9N24BpNrZNKkTkvJ+yWOIYR4Wyq OBPYMtM14cWIQVmu6fuIM2jc0v0aUiANsSqMfDhQuKb3xwv4VD3XMXVFJtFLdpE= =Huvb -----END PGP SIGNATURE----- --mojUlQ0s9EVzWg2t--