Re: drop_caches ...

[Zdenek Kabelac]

Markus napsal(a):
> > > > > > > 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".


Are you using binary  driver from NVidia ??
Maybe you should ask authors of this binary blob ?

Could you try to use for a while Vesa driver to see, if you are able to get 
same strange results ?

Zdenek
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