Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932808AbcCTBPL (ORCPT ); Sat, 19 Mar 2016 21:15:11 -0400 Received: from outbound.smtp.vt.edu ([198.82.183.121]:53879 "EHLO omr1.cc.vt.edu" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932597AbcCTBPG (ORCPT ); Sat, 19 Mar 2016 21:15:06 -0400 X-Mailer: exmh version 2.8.0 04/21/2012 with nmh-1.6+dev To: Alexander Potapenko Cc: Linux Memory Management List , LKML , Andrey Ryabinin Subject: Re: KASAN overhead? From: Valdis.Kletnieks@vt.edu In-Reply-To: References: <7300.1458333684@turing-police.cc.vt.edu> Mime-Version: 1.0 Content-Type: multipart/signed; boundary="==_Exmh_1458436494_2490P"; micalg=pgp-sha1; protocol="application/pgp-signature" Content-Transfer-Encoding: 7bit Date: Sat, 19 Mar 2016 21:14:54 -0400 Message-ID: <15565.1458436494@turing-police.cc.vt.edu> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2657 Lines: 73 --==_Exmh_1458436494_2490P Content-Type: text/plain; charset=us-ascii On Sat, 19 Mar 2016 13:13:59 +0100, Alexander Potapenko said: > Which GCC version were you using? Are you sure it didn't accidentally > enable the outline instrumentation (e.g. if the compiler is too old)? gcc --version gcc (GCC) 6.0.0 20160311 (Red Hat 6.0.0-0.16) * Fri Mar 11 2016 Jakub Jelinek 6.0.0-0.15 - update from the trunk Doesn't get much newer than that.. :) (Hmm.. possibly *too* new?) > > and saw an *amazing* slowdown. > Have you tried earlier KASAN versions? Is this a recent regression? First time I'd tried it, so no comparison point.. > Was KASAN reporting anything between these lines? Sometimes a recurring > warning slows everything down. Nope, it didn't report a single thing. > How did it behave after the startup? Was it still slow? After seeing how long it took to get to a single-user prompt, I didn't investigate further. It took 126 seconds to get here: [ 126.937247] audit: type=1327 audit(1458268293.617:100): proctitle="/usr/sbin/sulogin" compared to the more usual: [ 29.249260] audit: type=1327 audit(1458326938.276:100): proctitle="/usr/sbin/sulogin" (In both cases, there's a 10-12 second pause for entering a LUKS passphrase, so we're looking at about 110 seconds with KASAN versus about 17-18 without.) > Which machine were you using? Was it a real device or a VM? Running native on a Dell Latitude laptop.... (Based on the fact that you're asking questions rather than just saying it's expected behavior, I'm guessing I've once again managed to find a corner case of some sort. I'm more than happy to troubleshoot, if you can provide hints of what to try...) --==_Exmh_1458436494_2490P Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 Comment: Exmh version 2.5 07/13/2001 iQIVAwUBVu35jgdmEQWDXROgAQI8pA/+IRjIh3dGH0JVXeA7jTPz9GPvEsRYbH09 tz8zed8JR6NOu2XzpCfxTC2rAPInKekwEtviXaDrqAqmQm7rj5ckc1EpPviX9XlO 8PrqXWTLmZUB4daTgJrUxep0F1dCO05z1+61skgL2LGk4ke398GY94/oPoUHr08M n/NEFm8g6SU1xWaUwfQPTR6xTzbP6//ZzYQJkhl+NWw/9OtmYKP1lOhLRSsfPsl/ vxpmxRAASzVyN5m6+/uMDmgTVRojyMQKqjh9wKtukvJrwRGTHSL/3Hpz++d3aPwT ErtEg9/L9xtNW8f9XQl+3UPCcfg6VMKrnBl8emQET+2EWzO6xQFkg6thrwrBFKfo rEeLrjzwV3kV/6Hf5DTBTVui4OaXmlCOaLar+dE9Q0cqUDgEnfKsH1/dNxK2sUHe kuIKWbwps61ANqVZD4O4oYPq8w6TFOlMA/shnBPy6xkaGMRm20q2FTLlhxNR9EIf FHc16xGPnqn40fS3rn3I63KZOEdCiOvQ8RwVul0r+uUIuwljxE+VKg+ehysu/ZbT X8iXyRwNdgB/CwgcZvNQDjJE6eGNN7r/aUTQEXAJylOZjK2mHkcXdFd95nhCyZTn Yjx2rA1BxruaK+ozInnYEd5nwmTzPVcfldkwq9jtyAhlGe4wMCrsBmReOi38tgBQ yE7+gXRlCVc= =zssr -----END PGP SIGNATURE----- --==_Exmh_1458436494_2490P--