From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sasha Levin Subject: Re: [PATCH v2 6/8] kvm tools: Add rwlock wrapper Date: Mon, 30 May 2011 12:34:29 +0300 Message-ID: <1306748069.14564.52.camel@lappy> References: <1306744247-26051-1-git-send-email-levinsasha928@gmail.com> <1306744247-26051-6-git-send-email-levinsasha928@gmail.com> <20110530084309.GH30513@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: Ingo Molnar , kvm@vger.kernel.org, asias.hejun@gmail.com, gorcunov@gmail.com, prasadjoshi124@gmail.com, "Paul E. McKenney" To: Pekka Enberg Return-path: Received: from mail-ww0-f44.google.com ([74.125.82.44]:47084 "EHLO mail-ww0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754170Ab1E3Je7 (ORCPT ); Mon, 30 May 2011 05:34:59 -0400 Received: by wwa36 with SMTP id 36so3726661wwa.1 for ; Mon, 30 May 2011 02:34:58 -0700 (PDT) In-Reply-To: Sender: kvm-owner@vger.kernel.org List-ID: On Mon, 2011-05-30 at 12:29 +0300, Pekka Enberg wrote: > On Mon, May 30, 2011 at 11:43 AM, Ingo Molnar wrote: > > Testing idea: for example 'make test locking' could do the bzImage > > test-bootup, with rwlocks built instead of the brlocksj? > > > > Pekka might have more ideas about how a good locking test-suite > > should be done, as JATO has one, right? > > The current users of brlocks won't actually cause the guest to be > paused under load. That's the part I worry about breaking. So again, > the test case can be a simple as firing up 100-1000 threads where most > of them are taking the read lock but few of them racing to take the > write lock. It would mean we need that many VCPUs: current br_read_lock() doesn't really do anything, which means that running these tests with dummy threads won't work. > It's usually pretty easy to make buggy suspend/locking implementation > deadlock when run with more than one physical cores. > > Pekka -- Sasha.