Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752826Ab2JOMOk (ORCPT ); Mon, 15 Oct 2012 08:14:40 -0400 Received: from e23smtp07.au.ibm.com ([202.81.31.140]:57243 "EHLO e23smtp07.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752619Ab2JOMOg (ORCPT ); Mon, 15 Oct 2012 08:14:36 -0400 Message-ID: <507BFD2C.3010808@linux.vnet.ibm.com> Date: Mon, 15 Oct 2012 17:40:20 +0530 From: Raghavendra K T Organization: IBM User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:15.0) Gecko/20120911 Thunderbird/15.0.1 MIME-Version: 1.0 To: habanero@linux.vnet.ibm.com CC: Avi Kivity , Peter Zijlstra , Rik van Riel , "H. Peter Anvin" , Ingo Molnar , Marcelo Tosatti , Srikar , "Nikunj A. Dadhania" , KVM , Jiannan Ouyang , chegu vinod , LKML , Srivatsa Vaddagiri , Gleb Natapov , Andrew Jones Subject: Re: [PATCH RFC 1/2] kvm: Handle undercommitted guest case in PLE handler References: <20120921120000.27611.71321.sendpatchset@codeblue> <505C654B.2050106@redhat.com> <505CA2EB.7050403@linux.vnet.ibm.com> <50607F1F.2040704@redhat.com> <20121003122209.GA9076@linux.vnet.ibm.com> <506C7057.6000102@redhat.com> <506D69AB.7020400@linux.vnet.ibm.com> <506D83EE.2020303@redhat.com> <1349356038.14388.3.camel@twins> <506DA48C.8050200@redhat.com> <20121009185108.GA2549@linux.vnet.ibm.com> <1349837987.5551.182.camel@oc6622382223.ibm.com> <5075B63C.5030603@linux.vnet.ibm.com> <1349897783.22418.15.camel@oc2024037011.ibm.com> In-Reply-To: <1349897783.22418.15.camel@oc2024037011.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit x-cbid: 12101512-0260-0000-0000-000001FC4AC0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3838 Lines: 83 On 10/11/2012 01:06 AM, Andrew Theurer wrote: > On Wed, 2012-10-10 at 23:24 +0530, Raghavendra K T wrote: >> On 10/10/2012 08:29 AM, Andrew Theurer wrote: >>> On Wed, 2012-10-10 at 00:21 +0530, Raghavendra K T wrote: >>>> * Avi Kivity [2012-10-04 17:00:28]: >>>> >>>>> On 10/04/2012 03:07 PM, Peter Zijlstra wrote: >>>>>> On Thu, 2012-10-04 at 14:41 +0200, Avi Kivity wrote: >>>>>>> [...] >>> A big concern I have (if this is 1x overcommit) for ebizzy is that it >>> has just terrible scalability to begin with. I do not think we should >>> try to optimize such a bad workload. >>> >> >> I think my way of running dbench has some flaw, so I went to ebizzy. >> Could you let me know how you generally run dbench? > > I mount a tmpfs and then specify that mount for dbench to run on. This > eliminates all IO. I use a 300 second run time and number of threads is > equal to number of vcpus. All of the VMs of course need to have a > synchronized start. > > I would also make sure you are using a recent kernel for dbench, where > the dcache scalability is much improved. Without any lock-holder > preemption, the time in spin_lock should be very low: > > >> 21.54% 78016 dbench [kernel.kallsyms] [k] copy_user_generic_unrolled >> 3.51% 12723 dbench libc-2.12.so [.] __strchr_sse42 >> 2.81% 10176 dbench dbench [.] child_run >> 2.54% 9203 dbench [kernel.kallsyms] [k] _raw_spin_lock >> 2.33% 8423 dbench dbench [.] next_token >> 2.02% 7335 dbench [kernel.kallsyms] [k] __d_lookup_rcu >> 1.89% 6850 dbench libc-2.12.so [.] __strstr_sse42 >> 1.53% 5537 dbench libc-2.12.so [.] __memset_sse2 >> 1.47% 5337 dbench [kernel.kallsyms] [k] link_path_walk >> 1.40% 5084 dbench [kernel.kallsyms] [k] kmem_cache_alloc >> 1.38% 5009 dbench libc-2.12.so [.] memmove >> 1.24% 4496 dbench libc-2.12.so [.] vfprintf >> 1.15% 4169 dbench [kernel.kallsyms] [k] __audit_syscall_exit > Hi Andrew, I ran the test with dbench with tmpfs. I do not see any improvements in dbench for 16k ple window. So it seems apart from ebizzy no workload benefited by that. and I agree that, it may not be good to optimize for ebizzy. I shall drop changing to 16k default window and continue with other original patch series. Need to experiment with latest kernel. (PS: Thanks for pointing towards, perf in latest kernel. It works fine.) Results: dbench run for 120 sec 30 sec warmup 8 iterations using tmpfs base = 3.6.0-rc5 with ple handler optimization patch. x => base + ple_window = 4k + => base + ple_window = 16k * => base + ple_gap = 0 dbench 1x overcommit case ========================= N Min Max Median Avg Stddev x 8 5322.5 5519.05 5482.71 5461.0962 63.522276 + 8 5255.45 5530.55 5496.94 5455.2137 93.070363 * 8 5350.85 5477.81 5408.065 5418.4338 44.762697 dbench 2x overcommit case ========================== N Min Max Median Avg Stddev x 8 3054.32 3194.47 3137.33 3132.625 54.491615 + 8 3040.8 3148.87 3088.615 3088.1887 32.862336 * 8 3031.51 3171.99 3083.6 3097.4612 50.526977 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/