From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx161.postini.com [74.125.245.161]) by kanga.kvack.org (Postfix) with SMTP id 78E126B0070 for ; Thu, 7 Jun 2012 23:17:33 -0400 (EDT) Received: by qafl39 with SMTP id l39so653670qaf.9 for ; Thu, 07 Jun 2012 20:17:32 -0700 (PDT) Message-ID: <4FD16EC8.60502@gmail.com> Date: Thu, 07 Jun 2012 23:17:28 -0400 From: KOSAKI Motohiro MIME-Version: 1.0 Subject: Re: [PATCH 1/5] vmstat: Implement refresh_vm_stats() References: <20120601122118.GA6128@lizard> <1338553446-22292-1-git-send-email-anton.vorontsov@linaro.org> In-Reply-To: <1338553446-22292-1-git-send-email-anton.vorontsov@linaro.org> Content-Type: text/plain; charset=ISO-2022-JP Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Anton Vorontsov Cc: Pekka Enberg , Leonid Moiseichuk , KOSAKI Motohiro , Minchan Kim , Bartlomiej Zolnierkiewicz , John Stultz , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linaro-kernel@lists.linaro.org, patches@linaro.org, kernel-team@android.com (6/1/12 8:24 AM), Anton Vorontsov wrote: > This function forcibly flushes per-cpu vmstat diff counters to the > global counters. > > Note that we don't try to flush percpu pagesets, the pcp will be > still flushed once per 3 seconds. > > Signed-off-by: Anton Vorontsov No. This is insane. Your patch improved vmevent accuracy a _bit_. But instead of, decrease a performance of large systems. That's no good deal. 99% user never uses vmevent. MOREOVER, this patch don't solve vmevent accuracy issue AT ALL. because of, a second is enough big to make large inaccuracy. Modern cpus are fast. Guys, the fact is, user land monitor can't use implicit batch likes vmstat. That's a reason why perf don't use vmstat. I suggest you see perf APIs. It may bring you good inspiration. -- 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