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Date: Thu, 8 Apr 2010 11:28:50 +0200 From: Jan Kara <jack@...e.cz> To: Denys Fedorysychenko <nuclearcat@...learcat.com> Cc: Alexander Viro <viro@...iv.linux.org.uk>, linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org Subject: Re: endless sync on bdi_sched_wait()? 2.6.33.1 Hi, On Wed 31-03-10 19:07:31, Denys Fedorysychenko wrote: > I have a proxy server with "loaded" squid. On some moment i did sync, and > expecting it to finish in reasonable time. Waited more than 30 minutes, still > "sync". Can be reproduced easily. > > Here is some stats and info: > > Linux SUPERPROXY 2.6.33.1-build-0051 #16 SMP Wed Mar 31 17:23:28 EEST 2010 > i686 GNU/Linux > > SUPERPROXY ~ # iostat -k -x -d 30 > Linux 2.6.33.1-build-0051 (SUPERPROXY) 03/31/10 _i686_ (4 CPU) > > Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz > avgqu-sz await svctm %util > sda 0.16 0.01 0.08 0.03 3.62 1.33 88.94 > 0.15 1389.89 59.15 0.66 > sdb 4.14 61.25 6.22 25.55 44.52 347.21 24.66 > 2.24 70.60 2.36 7.49 > sdc 4.37 421.28 9.95 98.31 318.27 2081.95 44.34 > 20.93 193.21 2.31 24.96 > sdd 2.34 339.90 3.97 117.47 95.48 1829.52 31.70 > 1.73 14.23 8.09 98.20 > sde 2.29 71.40 2.34 27.97 22.56 397.81 27.74 > 2.34 77.34 1.66 5.04 > dm-0 0.00 0.00 0.19 0.02 3.48 0.02 32.96 > 0.05 252.11 28.05 0.60 > > Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz > avgqu-sz await svctm %util > sda 0.00 0.00 0.00 0.00 0.00 0.00 0.00 > 0.00 0.00 0.00 0.00 > sdb 0.00 54.67 2.93 26.87 12.27 326.13 22.71 > 2.19 73.49 1.91 5.68 > sdc 0.00 420.50 3.43 110.53 126.40 2127.73 39.56 > 23.82 209.00 2.06 23.44 > sdd 0.00 319.63 2.30 122.03 121.87 1765.87 30.37 > 1.72 13.83 7.99 99.37 > sde 0.00 71.67 0.83 30.63 6.93 409.33 26.46 > 2.66 84.68 1.51 4.76 > dm-0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 > 0.00 0.00 0.00 0.00 > > > CPU: 8.4% usr 7.7% sys 0.0% nic 50.7% idle 27.7% io 0.6% irq 4.7% sirq > Load average: 5.57 4.82 4.46 2/243 2032 > PID PPID USER STAT VSZ %MEM CPU %CPU COMMAND > 1769 1552 squid R 668m 8.3 3 11.7 /usr/sbin/squid -N > 1546 1545 root R 10800 0.1 2 6.0 /config/globax > /config/globax.conf > 1549 1548 root S 43264 0.5 2 1.5 /config/globax /config/globax- > dld.conf > 1531 2 root DW 0 0.0 0 0.3 [jbd2/sdd1-8] > 1418 1 root S 2500 0.0 3 0.0 /sbin/syslogd -R 80.83.17.2 > 1524 2 root SW 0 0.0 0 0.0 [flush-8:32] > 1525 2 root SW 0 0.0 1 0.0 [jbd2/sdc1-8] > 1604 2 root DW 0 0.0 0 0.0 [flush-8:48] > 1537 2 root SW 0 0.0 1 0.0 [jbd2/sde1-8] > 18 2 root SW 0 0.0 3 0.0 [events/3] > 1545 1 root S 3576 0.0 1 0.0 /config/globax > /config/globax.conf > 1548 1 root S 3576 0.0 0 0.0 /config/globax /config/globax- > dld.conf > 1918 1 ntp S 3316 0.0 3 0.0 /usr/sbin/ntpd -s > 1919 1 root S 3268 0.0 3 0.0 /usr/sbin/ntpd -s > 1 0 root S 2504 0.0 0 0.0 /bin/sh /init trynew trynew > trynew trynew > 1923 1257 root S 2504 0.0 1 0.0 /sbin/getty 38400 tty1 > 1924 1257 root S 2504 0.0 0 0.0 /sbin/getty 38400 tty2 > 1927 1257 root S 2504 0.0 0 0.0 /sbin/getty 38400 tty3 > 2015 2014 root S 2504 0.0 1 0.0 -ash > 2032 2015 root R 2504 0.0 3 0.0 top > 1584 1 root S 2500 0.0 1 0.0 /usr/bin/ifplugd -i eth0 -a -r > /etc/startup/rc.ifup -t 1 -u 1 -d 1 > 1592 1 root S 2500 0.0 1 0.0 /usr/bin/ifplugd -i eth2 -a -r > /etc/startup/rc.ifup -t 1 -u 1 -d 1 > 1587 1 root S 2500 0.0 1 0.0 /usr/bin/ifplugd -i eth1 -a -r > /etc/startup/rc.ifup -t 1 -u 1 -d 1 > 1595 1 root S 2500 0.0 1 0.0 /usr/bin/ifplugd -i eth3 -a -r > /etc/startup/rc.ifup -t 1 -u 1 -d 1 > 1257 1 root S 2500 0.0 0 0.0 init > 1420 1 root S 2500 0.0 1 0.0 /sbin/klogd > 1432 1 root S 2500 0.0 3 0.0 /usr/sbin/telnetd -f > /etc/issue.telnet > 1552 1 root S 2500 0.0 1 0.0 /bin/sh /bin/squidloop > 1743 1742 root S 2500 0.0 3 0.0 ash -c gs newkernel > 1744 1743 root S 2500 0.0 0 0.0 /bin/sh /bin/gs newkernel > 1753 1744 root D 2368 0.0 0 0.0 sync > > > SUPERPROXY ~ # cat /proc/1753/stack > [<c019a93c>] bdi_sched_wait+0x8/0xc > [<c019a807>] wait_on_bit+0x20/0x2c > [<c019a9af>] sync_inodes_sb+0x6f/0x10a > [<c019dd53>] __sync_filesystem+0x28/0x49 > [<c019ddf3>] sync_filesystems+0x7f/0xc0 > [<c019de7a>] sys_sync+0x1b/0x2d > [<c02f7a25>] syscall_call+0x7/0xb > [<ffffffff>] 0xffffffff Hmm, I guess you are observing the problem reported in https://bugzilla.kernel.org/show_bug.cgi?id=14830 There seem to be several issues in the per-bdi writeback code that cause sync on a busy filesystem to last almost forever. To that bug are attached two patches that fix two issues but apparently it's not all. I'm still looking into it... Honza -- Jan Kara <jack@...e.cz> SUSE Labs, CR -- 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/
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