lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Thu, 29 Jan 2015 11:32:43 -0600 (CST) From: Christoph Lameter <cl@...ux.com> To: Michal Hocko <mhocko@...e.cz> cc: Vinayak Menon <vinmenon@...eaurora.org>, linux-mm@...ck.org, linux-kernel@...r.kernel.org, akpm@...ux-foundation.org, hannes@...xchg.org, vdavydov@...allels.com, mgorman@...e.de, minchan@...nel.org Subject: Re: [PATCH v2] mm: vmscan: fix the page state calculation in too_many_isolated On Fri, 16 Jan 2015, Michal Hocko wrote: > __round_jiffies_relative can easily make timeout 2HZ from 1HZ. Now we > have vmstat_shepherd which waits to be queued and then wait to run. When > it runs finally it only queues per-cpu vmstat_work which can also end > up being 2HZ for some CPUs. So we can indeed have 4 seconds spent just > for queuing. Not even mentioning work item latencies. Especially when > workers are overloaded e.g. by fs work items and no additional workers > cannot be created e.g. due to memory pressure so they are processed only > by the workqueue rescuer. And latencies would grow a lot. Here is a small fix to ensure that the 4 seconds interval does not happen: Subject: vmstat: Reduce time interval to stat update on idle cpu It was noted that the vm stat shepherd runs every 2 seconds and that the vmstat update is then scheduled 2 seconds in the future. This yields an interval of double the time interval which is not desired. Change the shepherd so that it does not delay the vmstat update on the other cpu. We stil have to use schedule_delayed_work since we are using a delayed_work_struct but we can set the delay to 0. Signed-off-by: Christoph Lameter <cl@...ux.com> Index: linux/mm/vmstat.c =================================================================== --- linux.orig/mm/vmstat.c +++ linux/mm/vmstat.c @@ -1435,8 +1435,8 @@ static void vmstat_shepherd(struct work_ if (need_update(cpu) && cpumask_test_and_clear_cpu(cpu, cpu_stat_off)) - schedule_delayed_work_on(cpu, &per_cpu(vmstat_work, cpu), - __round_jiffies_relative(sysctl_stat_interval, cpu)); + schedule_delayed_work_on(cpu, + &per_cpu(vmstat_work, cpu), 0); put_online_cpus(); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists