Date: Thu, 16 Feb 2017 15:20:29 -0700 From: Alan Somers <asomers@freebsd.org> To: Dustin Wenz <dustinwenz@ebureau.com> Cc: FreeBSD <freebsd-stable@freebsd.org> Subject: Re: Jailed periodic daily scripts smashing CPU Message-ID: <CAOtMX2hb%2BmoGWZFuUjrhO-A6NPg5zRsgs3QDRA2Ja1eATwUCsQ@mail.gmail.com> In-Reply-To: <321260F8-95D8-4C21-90B5-FDB0F6FF98F9@ebureau.com> References: <321260F8-95D8-4C21-90B5-FDB0F6FF98F9@ebureau.com>
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Is the problem caused by newsyslog or by the periodic scripts? Newsyslog normally runs from cron directly, not through periodic. In any case, here are a few suggestions: 1) Turn on cron jitter, as you suggested. Even if 60s isn't enough, it can't hurt. 2) Try gz compression instead of xz compression to see if it's faster 3) Manually edit the jails' /etc/crontab files to hardcode some variability into their newsyslog and/or periodic run times 4) If the problem is actually being caused by periodic instead of newsyslog, tell me which script it is and how much jitter you want. I am coincidentally changing how periodic manages jitter right now. -Alan On Thu, Feb 16, 2017 at 2:47 PM, Dustin Wenz <dustinwenz@ebureau.com> wrote= : > I have a number of servers with roughly 60 jails running on each of them.= On these hosts, I've had to disable the periodic security scans due to ove= rly high disk load when they run (which is redundant in jails anyway). Howe= ver, I still have an issue at 3:01am where the CPU is consumed by dozens of= 'xz -c' processes. This is apparently daily log rolling, which I can't exa= ctly disable. > > The effect is that our processing applications experience a major slowdow= n for about 15 seconds every morning, which is just enough that it's starti= ng to get people's attention. > > What is the best way to mitigate this? I'm aware of the cron jitter featu= re, but I'm not sure of the 60-second jitter maximum would be enough (espec= ially if I wanted to start utilizing more jails). > > - .Dustin > _______________________________________________ > freebsd-stable@freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-stable > To unsubscribe, send any mail to "freebsd-stable-unsubscribe@freebsd.org"
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