Date: Sat, 7 Sep 2002 20:08:18 +0200 From: Bernd Walter <ticso@cicely9.cicely.de> To: "Michael R. Wayne" <wayne@staff.msen.com> Cc: hackers@FreeBSD.ORG Subject: Re: Excessive swap usage w/ 4.6 Message-ID: <20020907180817.GG26637@cicely9.cicely.de> In-Reply-To: <200209062031.QAA05990@manor.msen.com> References: <200209062031.QAA05990@manor.msen.com>
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On Fri, Sep 06, 2002 at 04:31:18PM -0400, Michael R. Wayne wrote: > > After having moved servers from 4.3 and 4.5 to 4.6, we are noticing > that swap indicates much higher usage. Today, one of our squid > cache servers hit (and stayed at) 50% swap utilization so I decided > to do some digging. > > This machine has 512 MB physical RAM in it and is running > FreeBSD 4.5-RELEASE-p7 > > Here's a ps with some cruft removed and columns widened for readability. > > > ps -axel > CPU PRI NI VSZ RSS WCHAN STAT TT TIME COMMAND > 0 -18 0 0 0 sched DLs ?? 0:00.00 (swapper) > 0 10 0 544 116 wait ILs ?? 0:00.31 /sbin/init -- > 0 -18 0 0 0 psleep DL ?? 5:30.16 (pagedaemon) > 0 18 0 0 0 psleep DL ?? 0:00.04 (vmdaemon) > 0 -18 0 0 0 psleep DL ?? 0:33.61 (bufdaemon) > 0 -2 0 0 0 vlruwt DL ?? 0:29.52 (vnlru) > 0 18 0 0 0 syncer DL ?? 29:36.89 (syncer) > 0 2 0 948 340 select Ss ?? 0:15.27 /usr/sbin/syslogd -s > 0 2 0 1300 352 select Ss ?? 3:52.69 ntpd -p /var/run/ntpd.pid > 0 2 0 1064 560 select Is ?? 0:00.18 /usr/sbin/inetd -wW > 0 10 0 984 216 nanslp Is ?? 0:15.08 /usr/sbin/cron > 28 2 0 2136 264 select Is ?? 3:00.12 /usr/local/sbin/sshd > 0 10 0 2940 0 wait IWs ?? 0:00.00 () /usr/local/sbin/squid > 4 2 0 398380 381916 poll S ?? 286:58.56 (squid) (squid) > 0 -6 0 860 176 piperd Ss ?? 1:35.35 (unlinkd) (unlinkd) > 0 2 0 4792 512 select Ss ?? 0:01.48 sshd: > 0 2 0 2732 1920 select Ss ?? 0:02.73 /usr/local/sbin/gated > 0 2 0 2096 1464 select Ss ?? 0:00.08 /usr/local/sbin/httpd > 0 2 0 2504 1660 accept I ?? 0:00.01 /usr/local/sbin/httpd > 0 2 0 2512 1668 accept I ?? 0:00.01 /usr/local/sbin/httpd > 0 18 0 1584 820 pause Ss p0 0:00.51 SSH_CLIENT= > 0 28 0 416 172 - R+ p0 0:00.00 SSH_CLIENT= > 0 3 0 948 528 ttyin Is+ v0 0:00.00 /usr/libexec/getty Pc ttyv0 > 0 3 0 948 524 ttyin Is+ v1 0:00.00 /usr/libexec/getty Pc ttyv1 > ======= ======= > Totals 427,688 393,208 > -393,208 > ======= > 34,480 So, swap usage should be about this much. But: > > pstat -s > Device 1K-blocks Used Avail Capacity Type > /dev/ad0s1b 614272 304792 309480 50% Interleaved > > This seems very excessive as well as unjustified. Is there some > way I can find out if I have a "swap leak" or some other way to > figure out what is going on? As I mentioned, we noticed a significant > increase in swap usage on many servers between 4.3 or 4.5 and 4.6 If you squid proccess was paged it will keep the swap allocation until the memory is freed. In case pages need to be transfered to swap again it doesn't need to be allocated again - and if the page is unmodified in respect to the swap backed version you even spare the disk access. -- B.Walter COSMO-Project http://www.cosmo-project.de ticso@cicely.de Usergroup info@cosmo-project.de To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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