Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752243Ab0LJRS0 (ORCPT ); Fri, 10 Dec 2010 12:18:26 -0500 Received: from mail-ey0-f171.google.com ([209.85.215.171]:46279 "EHLO mail-ey0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750753Ab0LJRSZ (ORCPT ); Fri, 10 Dec 2010 12:18:25 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=subject:from:to:cc:in-reply-to:references:content-type:date :message-id:mime-version:x-mailer:content-transfer-encoding; b=v1kNbDDGQ1aGdXleM2GdDBZ1yyR8V/QmwLdDrQhp0LAg6PWOibS5zLpN5eZaBEzSYF 7hn++R6sO7s9uTaldTrIs+lyqHgoHonbPK0IKmAejS3jxTYxzSIdxGIhYdXng9AEwU+X qELjEy8ozkwC7dPw6fKbx0OtYPpTM6QZ8SZss= Subject: Re: [BUG] 2.6.37-rc3 massive interactivity regression on ARM From: Eric Dumazet To: Peter Zijlstra Cc: Venkatesh Pallipadi , Russell King - ARM Linux , Mikael Pettersson , Ingo Molnar , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, John Stultz , Christoph Lameter In-Reply-To: <1291988866.6803.171.camel@twins> References: <20101208142814.GE9777@n2100.arm.linux.org.uk> <1291851079-27061-1-git-send-email-venki@google.com> <1291899120.29292.7.camel@twins> <1291917330.6803.7.camel@twins> <1291920939.6803.38.camel@twins> <1291936593.13513.3.camel@laptop> <1291975704.6803.59.camel@twins> <1291987065.6803.151.camel@twins> <1291987635.6803.161.camel@twins> <1291988866.6803.171.camel@twins> Content-Type: text/plain; charset="UTF-8" Date: Fri, 10 Dec 2010 18:18:20 +0100 Message-ID: <1292001500.3580.268.camel@edumazet-laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1556 Lines: 58 Le vendredi 10 décembre 2010 à 14:47 +0100, Peter Zijlstra a écrit : > Full patch.. > unt_system_vtime(struct task_struct *curr) > { > unsigned long flags; > + s64 delta; > int cpu; > - u64 now, delta; > > if (!sched_clock_irqtime) > return; > > local_irq_save(flags); > - > cpu = smp_processor_id(); > - now = sched_clock_cpu(cpu); > - delta = now - per_cpu(irq_start_time, cpu); > - per_cpu(irq_start_time, cpu) = now; > - /* > - * We do not account for softirq time from ksoftirqd here. > - * We want to continue accounting softirq time to ksoftirqd thread > - * in that case, so as not to confuse scheduler with a special task > - * that do not consume any time, but still wants to run. > - */ > + delta = sched_clock_cpu(cpu) - per_cpu(irq_start_time, cpu); > + per_cpu(irq_start_time, cpu) += delta; We should add some checkpatch warning to any new per_cpu() use. delta = sched_clock_cpu(cpu) - __this_cpu_read(irq_start_time); __this_cpu_add(irq_start_time, delta); Also irq_time_write_begin() and irq_time_write_end() could be faster (called for current cpu) static inline void irq_time_write_begin(void) { __this_cpu_inc(irq_time_seq.sequence); smp_wmb(); } static inline void irq_time_write_end(void) { smp_wmb(); __this_cpu_inc(irq_time_seq.sequence); } -- 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/