Re: drop_caches ...

Markus
2009-03-04T13:47:54Z

> >>>>> 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!
> >
> > So you don't have lots of mapped pages(Mapped=51M) or tmpfs files.
It's
> > strange to me that there are so many undroppable cached
pages(Cached=359M),
> > and most of them lie out of the LRU queue(Active+Inactive
file=53M)...
> >
> > Anyone have better clues on these 'hidden' pages?
>
> Maybe try this:
>
> cat /proc/`pidof X`/smaps | grep drm | wc -l
>
> you will see some growing numbers.
>
> Also check cat /proc/dri/0/gem_objects
> there should be some number # object bytes - which should be close to
your
> missing cached pages.
>
>
> If you are using Intel GEM driver - there is some unlimited caching
issue
>
> see: http://bugs.freedesktop.org/show_bug.cgi?id=20404
>
# cat /proc/`pidof X`/smaps | grep drm | wc -l
0
# cat /proc/dri/0/gem_objects
cat: /proc/dri/0/gem_objects: No such file or directory

I use Xorg 1.3 with an nvidia gpu. Dont know if I use a "Intel GEM
driver".

Btw I am running a 2.6.28.2.

Thanks.
Markus