Hi Guys, I have a file-server that has plenty of memory to cache most of the things that I use. But after I've upgraded the machine it seems to expire things from the cache even when there is zero memory pressure.
The case that irritates me most is my mailbox. Ok, I should clean it out, but also my linux-kernel mailbox has 20k messages (= 1 month). When I open such a mailbox in mutt, it takes 2 minutes for it to read all the messages. If I quit and restart, it takes less than a second. I've resorted to a workaround: every 30 seconds: head Mailbox/cur/* . That worked. Oh, before a recent upgrade all this worked as I expected: Once a day, after the backup had run, scanning the mailbox takes a while and then the rest of the day things are quick. Then I gathered: Other people must have the same problem. It is probably a "tuning" setting which works for desktop machines, but not for my server. So I've googled a few "tuning your Linux system" pages and all I could think of that might relate to my problem is "swappiness". I've decreased the value from 100 (in a few steps) to 5 now, and this seems to help somewhat. But still after a few minutes, the buffer cache drops my maildir, and starting mutt takes a long time again. All this with the machine reporting 11Gb or more of RAM "Free" (empty). With the default swappiness, I've tested that in a minute already some of the maildir gets ejected from the cache, while when accessing all files every 30 seconds seems to keep them cached. Kernel: from Ubuntu 14.04, 3.13.0-19-generic 32-bit userspace 16Gb RAM installed. Disks: 3x 3T in RAID5 ganglia shows the server memory graph as follows: http://prive.bitwizard.nl/server_mem.png All other computers have a "nice" filled graph there. So, is there a bug in my kernel or am I missing an important tuning parameter? Roger. -- ** [email protected] ** http://www.BitWizard.nl/ ** +31-15-2600998 ** ** Delftechpark 26 2628 XH Delft, The Netherlands. KVK: 27239233 ** *-- BitWizard writes Linux device drivers for any device you may have! --* The plan was simple, like my brother-in-law Phil. But unlike Phil, this plan just might work. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
