HI Thiago ! Thank you a lot for your very interesting comment !
In fact I get the same limitation with a 8GB memory server. Please correct me if I¹m wrong : My system has only 8GB of memory. Thus I can assume that the kernel should have stared to write dirty mmap'ed pages longer in advance than your server does. But the very high loads I¹ve seen are only occuring once the cache became close to 20GB+. Why is that ? I still don¹t understand this 20GB+ limitation. I addition of the vmstat and ps that I collect regularly, I will add an iostat to watch the disk activity. Jef Le 27/04/11 00:26, « Thiago Figueiro » a écrit : > From: Jean-Francois Laurens > >> > Hi there, > >> > Apr 20 21:48:43 server-01-39 varnishd[21087]: Child (5372) not responding >> > to CLI, killing it. > > Hi! I'm a bit late to the discussion (happy Easter everyone!) but we came > across this issue on Linux earlier this year. > > You didn't send charts for your disk IO but I'm betting it looks busy. If > this is so, it may be the kernel pre-empting writing of dirty mmap pages to > disk. > > I investigated the issue at the time and found that on the RHEL 5 vanilla > kernel the Varnish child was being blocked by kernel IO. This caused the > parent pings to time-out: > > http://microrants.blogspot.com/2010/07/varnish-and-linux-io-bottleneck.html > > > TL;DR: > echo 0 > /proc/sys/vm/flush_mmap_pages > > > > Good luck, > Thiago. > > > ______________________________________________________ > CONFIDENTIALITY NOTICE > This electronic mail message, including any and/or all attachments, is for the > sole use of the intended recipient(s), and may contain confidential and/or > privileged information, pertaining to business conducted under the direction > and supervision of the sending organization. All electronic mail messages, > which may have been established as expressed views and/or opinions (stated > either within the electronic mail message or any of its attachments), are left > to the sole responsibility of that of the sender, and are not necessarily > attributed to the sending organization. Unauthorized interception, review, > use, disclosure or distribution of any such information contained within this > electronic mail message and/or its attachment(s), is (are) strictly > prohibited. If you are not the intended recipient, please contact the sender > by replying to this electronic mail message, along with the destruction all > copies of the original electronic mail message (along with any attachments). > ______________________________________________________ > > Jean-Francois Laurens > Ingénieur Système Unix > Resources et Développement > Secteur Backend > RTS - Radio Télévision Suisse > Quai Ernest-Ansermet 20 > Case postale 234 > CH - 1211 Genève 8 > T +41 (0)58 236 81 63 >
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