Re: drop_caches ...

From: Markus
Date: Wed Mar 04 2009 - 06:29:59 EST


> > > The memory mapped pages won't be dropped in this way.
> > > "cat /proc/meminfo" will show you the number of mapped pages.
> >
> > # sync ; echo 3 > /proc/sys/vm/drop_caches ; free -m ;
cat /proc/meminfo
> > total used free shared buffers
> > cached
> > Mem: 3950 3262 688 0 0
> > 359
> > -/+ buffers/cache: 2902 1047
> > Swap: 5890 1509 4381
> > MemTotal: 4045500 kB
> > MemFree: 705180 kB
> > Buffers: 508 kB
> > Cached: 367748 kB
> > SwapCached: 880744 kB
> > Active: 1555032 kB
> > Inactive: 1634868 kB
> > Active(anon): 1527100 kB
> > Inactive(anon): 1607328 kB
> > Active(file): 27932 kB
> > Inactive(file): 27540 kB
> > Unevictable: 816 kB
> > Mlocked: 0 kB
> > SwapTotal: 6032344 kB
> > SwapFree: 4486496 kB
> > Dirty: 0 kB
> > Writeback: 0 kB
> > AnonPages: 2378112 kB
> > Mapped: 52196 kB
> > Slab: 65640 kB
> > SReclaimable: 46192 kB
> > SUnreclaim: 19448 kB
> > PageTables: 28200 kB
> > NFS_Unstable: 0 kB
> > Bounce: 0 kB
> > WritebackTmp: 0 kB
> > CommitLimit: 8055092 kB
> > Committed_AS: 4915636 kB
> > VmallocTotal: 34359738367 kB
> > VmallocUsed: 44580 kB
> > VmallocChunk: 34359677239 kB
> > DirectMap4k: 3182528 kB
> > DirectMap2M: 1011712 kB
> >
> > The cached reduced to 359 MB (after the dropping).
> > I dont know where to read the "number of mapped pages".
> > "Mapped" is about 51 MB.
>
> Does your tmpfs store lots of files?

Dont think so:

# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/md6 14G 8.2G 5.6G 60% /
udev 10M 304K 9.8M 3% /dev
cachedir 4.0M 100K 4.0M 3% /lib64/splash/cache
/dev/md4 19G 15G 3.1G 83% /home
/dev/md3 8.3G 4.5G 3.9G 55% /usr/portage
shm 2.0G 0 2.0G 0% /dev/shm
/dev/md1 99M 19M 76M 20% /boot

# mount
/dev/md6 on / type ext3 (rw,noatime,nodiratime,barrier=0)
/proc on /proc type proc (rw,noexec,nosuid,noatime,nodiratime)
sysfs on /sys type sysfs (rw,nosuid,nodev,noexec)
udev on /dev type tmpfs (rw,nosuid,size=10240k,mode=755)
devpts on /dev/pts type devpts (rw,nosuid,noexec,gid=5,mode=620)
cachedir on /lib64/splash/cache type tmpfs (rw,size=4096k,mode=644)
/dev/md4 on /home type ext3 (rw,noatime,nodiratime,barrier=0)
/dev/md3 on /usr/portage type ext4 (rw,noatime,nodiratime,barrier=0)
shm on /dev/shm type tmpfs (rw,noexec,nosuid,nodev)
usbfs on /proc/bus/usb type usbfs
(rw,noexec,nosuid,devmode=0664,devgid=85)
automount(pid6507) on /mnt/.autofs/misc type autofs
(rw,fd=4,pgrp=6507,minproto=2,maxproto=4)
automount(pid6521) on /mnt/.autofs/usb type autofs
(rw,fd=4,pgrp=6521,minproto=2,maxproto=4)
/dev/md1 on /boot type ext2 (rw,noatime,nodiratime)

I dont know what exactly all that memory is used for. It varies from
about 300 MB to up to one GB.
Tell me where to look and I will!

Thanks!

Markus
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