Hello!



I have a small problem. Maybe its just a misunderstanding but I cant 

solve it.



I think that writing "3" to drop_caches should drop all buffers and 

caches which are already written. So its recommended to put a "sync" 

infront of it.

So I did "free -m ; sync ; echo 3 > /proc/sys/vm/drop_caches ; free -m"

And it gave me:



             total       used       free     shared    buffers     cached

Mem:          3950       3922         28          0          1        879

-/+ buffers/cache:       3041        909

Swap:         5342        205       5136



             total       used       free     shared    buffers     cached

Mem:          3950       3907         43          0          0        864

-/+ buffers/cache:       3041        908

Swap:         5341        206       5135



So the buffer was 1 and is 0 afterthat. But cached is at 879 MB before 

and is still 864 MB (!!!) after that!



I am at swappiness=0 and when I remove and readd one swap-partition 

after another (so there is always swap). It will keep the cached and 

put the swapped memory on other swaps?!



I _think_ thats not the way it should go?



It would be really kind if someone could explain that issue and 

what "cached" is at all!



Have a nice day...

Markus



PS: Please CC me as I am not subscribed.


2.6.28でGEMが入ってからメモリが足りなくなった－。リークだーと騒ぐ人が増えたね。



# echo 3 > /proc/sys/vm/drop_caches

してもcached 欄が減らないぞーというわけ。

さて、このcached欄であるが、/proc/meminfoの "Cached:"フィールドの数字を表示している。
で、以下の結果をみると



I rebooted in console without the nvidia-module loaded and have the same 

results (updated to 2.6.28.7 btw):

# sync ; echo 3 > /proc/sys/vm/drop_caches ; free -m ; cat /proc/meminfo

             total       used       free     shared    buffers     

cached

Mem:          3950       1647       2303          0          0        

924

-/+ buffers/cache:        722       3228

Swap:         5890          0       5890

MemTotal:        4045444 kB

MemFree:         2358944 kB

Buffers:             544 kB

Cached:           946624 kB

SwapCached:            0 kB

Active:          1614756 kB

Inactive:           7632 kB

Active(anon):    1602476 kB

Inactive(anon):        0 kB

Active(file):      12280 kB

Inactive(file):     7632 kB

Unevictable:           0 kB

Mlocked:               0 kB

SwapTotal:       6032344 kB

SwapFree:        6032344 kB

Dirty:                72 kB

Writeback:            32 kB

AnonPages:        675224 kB

Mapped:            17756 kB

Slab:              19936 kB

SReclaimable:       9652 kB

SUnreclaim:        10284 kB

PageTables:         8296 kB

NFS_Unstable:          0 kB

Bounce:                0 kB

WritebackTmp:          0 kB

CommitLimit:     8055064 kB

Committed_AS:    3648088 kB

VmallocTotal:   34359738367 kB

VmallocUsed:       10616 kB

VmallocChunk:   34359716459 kB

DirectMap4k:        6080 kB

DirectMap2M:     4188160 kB


Cachedと{In}Active(file) が合ってないように見えるが、これはtmpfs用のページが{In}Active(anon)にチャージされる仕様のため。
ようするに Cached:の900MはほとんどがtmpfsファイルでActive(anon)にチャージされていると考えるとつじつまがある。

で、このあと、そんなのマウントしてないとか議論になるのだが、Intelドライバつかっていると、カーネル内部でGEM用にこっそりマウントしてこっそり確保しまくるんだな。これが。

だから、ドライバが900Mも使うな！と抗議するのが正しい




http://bugs.freedesktop.org/show_bug.cgi?id=20404