George Dancheff wrote: > > Hi, I just compiled some kernels 2.4.x series , and it > seems to me that all these builds prefer to use my > swap space instead of my free memory , so the > performance dropped :((( . I noticed when the mashine > is not overloaded , free outputs the following : > debian:/# free > total used free shared > buffers cached > Mem: 60752 59792 960 0 > 1084 34508 > -/+ buffers/cache: 24200 36552 > Swap: 104384 33076 71308 > debian:/# > > The mashine uses 1/3 of my swap , but i just started a > X session with Netscape and KMail . Also Shared must > be different from 0 ..., but it is not . Couldn't get > why kernel prefers my swap than my free RAM . > When the mashine is really overloaded Shared field > from the 'free' output remains 0 , and swap activity > really get enormous . > > Anyone able to explain why the 2.4 kernel prefers swap > instead of free RAM ???
as I see you only have almost 1 Mb of RAM free, the kernel allways keep some memory (about 1-2 Mb of RAM) free; I belive that this is tunable by changing the source before recompile or through sysctl if you compiled support for that, altthough I don't know the exact parameter. also, you may check some documentation about the new shared memory model (2.4.x); you may need to add to your fstab the line: shm /dev/shm shm defaults 0 0 if you have a 2.4.x=< 2.4.3 or: tmpfs /dev/shm tmpfs defaults 0 0 if you have 2.4.x >= 2.4.4. note that you have to compile support for it (shm) in the kernel. and for the 2.4.x kernels free allways reports 0 for shared memories, I don't know why (I think I read it in the man); maybe a newer version would fix that... Regards Dragos Bucharest, Romania