From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx142.postini.com [74.125.245.142]) by kanga.kvack.org (Postfix) with SMTP id C30BF6B0062 for ; Wed, 21 Nov 2012 06:47:34 -0500 (EST) Date: Wed, 21 Nov 2012 11:47:28 +0000 From: Mel Gorman Subject: Re: [PATCH] x86/mm: Don't flush the TLB on #WP pmd fixups Message-ID: <20121121114728.GZ8218@suse.de> References: <20121119162909.GL8218@suse.de> <20121120060014.GA14065@gmail.com> <20121120074445.GA14539@gmail.com> <20121120090637.GA14873@gmail.com> <20121120120251.GA15742@gmail.com> <20121120123156.GA15798@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20121120123156.GA15798@gmail.com> Sender: owner-linux-mm@kvack.org List-ID: To: Ingo Molnar Cc: David Rientjes , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Peter Zijlstra , Paul Turner , Lee Schermerhorn , Christoph Lameter , Rik van Riel , Andrew Morton , Andrea Arcangeli , Linus Torvalds , Thomas Gleixner , Johannes Weiner , Hugh Dickins On Tue, Nov 20, 2012 at 01:31:56PM +0100, Ingo Molnar wrote: > > * Ingo Molnar wrote: > > > * Ingo Molnar wrote: > > > > > numa/core profile: > > > > > > 95.66% perf-1201.map [.] 0x00007fe4ad1c8fc7 > > > 1.70% libjvm.so [.] 0x0000000000381581 > > > 0.59% [vdso] [.] 0x0000000000000607 > > > 0.19% [kernel] [k] do_raw_spin_lock > > > 0.11% [kernel] [k] generic_smp_call_function_interrupt > > > 0.11% [kernel] [k] timekeeping_get_ns.constprop.7 > > > 0.08% [kernel] [k] ktime_get > > > 0.06% [kernel] [k] get_cycles > > > 0.05% [kernel] [k] __native_flush_tlb > > > 0.05% [kernel] [k] rep_nop > > > 0.04% perf [.] add_hist_entry.isra.9 > > > 0.04% [kernel] [k] rcu_check_callbacks > > > 0.04% [kernel] [k] ktime_get_update_offsets > > > 0.04% libc-2.15.so [.] __strcmp_sse2 > > > > > > No page fault overhead (see the page fault rate further below) > > > - the NUMA scanning overhead shows up only through some mild > > > TLB flush activity (which I'll fix btw). > > > > The patch attached below should get rid of that mild TLB > > flushing activity as well. > > This has further increased SPECjbb from 203k/sec to 207k/sec, > i.e. it's now 5% faster than mainline - THP enabled. > > The profile is now totally flat even during a full 32-WH SPECjbb > run, with the highest overhead entries left all related to timer > IRQ processing or profiling. That is on a system that should be > very close to yours. > This is a stab in the dark but are you always running with profiling enabled? I have not checked this with perf but a number of years ago I found that oprofile could distort results really badly (7-30% depending on the workload at the time) when I was evalating hugetlbfs and THP. In some cases I would find that profiling would show that a patch series improved performance when the same series showed regressions if profiling was disabled. The sampling rate had to be reduced quite a bit to avoid this effect. -- Mel Gorman SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org