From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751629AbcGOQ1Y (ORCPT ); Fri, 15 Jul 2016 12:27:24 -0400 Received: from mail-wm0-f65.google.com ([74.125.82.65]:32864 "EHLO mail-wm0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751196AbcGOQ1V (ORCPT ); Fri, 15 Jul 2016 12:27:21 -0400 Subject: Re: [PATCH 01/14] resource limits: foundation for resource highwater tracking To: nicolas.dichtel@6wind.com, linux-kernel@vger.kernel.org References: <1468578983-28229-1-git-send-email-toiwoton@gmail.com> <1468578983-28229-2-git-send-email-toiwoton@gmail.com> <5788DBE4.50406@6wind.com> Cc: Jonathan Corbet , Ingo Molnar , Peter Zijlstra , Balbir Singh , "David S. Miller" , Markus Elfring , Thomas Gleixner , Rik van Riel , "open list:DOCUMENTATION" From: Topi Miettinen Openpgp: id=A0F2EB0D8452DA908BEC8E911CF9ADDBD610E936 Message-ID: Date: Fri, 15 Jul 2016 16:27:13 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Icedove/45.1.0 MIME-Version: 1.0 In-Reply-To: <5788DBE4.50406@6wind.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/15/16 12:49, Nicolas Dichtel wrote: > Le 15/07/2016 12:35, Topi Miettinen a écrit : >> There are many basic ways to control processes, including capabilities, >> cgroups and resource limits. However, there are far fewer ways to find out >> useful values for the limits, except blind trial and error. >> >> Prepare a foundation for resource highwater tracking. >> >> The collected highwater marks for the resources can be seen using >> taskstats netlink interface. >> >> This depends on CONFIG_TASK_XACCT. >> >> Signed-off-by: Topi Miettinen >> --- > [snip] >> @@ -63,6 +65,8 @@ int print_task_context_switch_counts; >> /* Maximum number of cpus expected to be specified in a cpumask */ >> #define MAX_CPUS 32 >> >> +#define TASKSTATS_VERSION_WITH_RESOURCE 9 >> + >> struct msgtemplate { >> struct nlmsghdr n; >> struct genlmsghdr g; > [snip] >> @@ -252,6 +276,22 @@ static void print_ioacct(struct taskstats *t) >> (unsigned long long)t->cancelled_write_bytes); >> } >> >> +static void print_racct(const struct taskstats *t) >> +{ >> + int i; >> + >> + if (t->version < TASKSTATS_VERSION_WITH_RESOURCE) { >> + printf("kernel too old (%d < %d)\n", t->version, >> + TASKSTATS_VERSION_WITH_RESOURCE); >> + return; >> + } > > [snip] >> diff --git a/include/uapi/linux/taskstats.h b/include/uapi/linux/taskstats.h >> index 2466e55..8c65194 100644 >> --- a/include/uapi/linux/taskstats.h >> +++ b/include/uapi/linux/taskstats.h >> @@ -33,7 +33,7 @@ >> */ >> >> >> -#define TASKSTATS_VERSION 8 >> +#define TASKSTATS_VERSION 9 >> #define TS_COMM_LEN 32 /* should be >= TASK_COMM_LEN >> * in linux/sched.h */ >> >> @@ -163,6 +163,14 @@ struct taskstats { >> /* Delay waiting for memory reclaim */ >> __u64 freepages_count; >> __u64 freepages_delay_total; >> + /* Per-task storage I/O accounting ends */ >> + >> +#define TASKSTATS_HAS_LIMIT_ACCOUNTING >> + /* Per-task resource accounting starts */ >> + __u64 resource_hiwater[RLIM_NLIMITS]; /* high-watermark of >> + RLIMIT >> + resources */ >> + /* Per-task resource accounting ends */ >> }; > Why playing with version number? It complexifies the (userland) code and > existing applications break when the kernel is updated. > Goal of netlink is to be easily extensible. By adding a new attribute, existing > userspace tools won't break. I just followed this text in taskstats.h. Does that give wrong advice? * The struct is versioned. Newer versions should only add fields to * the bottom of the struct to maintain backward compatibility. * * * To add new fields * a) bump up TASKSTATS_VERSION * b) add comment indicating new version number at end of struct * c) add new fields after version comment; maintain 64-bit alignment -Topi > > > Regards, > Nicolas >