On Aug 26 2007 12:49, Fred Tyler wrote: >> >> So I guess you are not seeing any memory leak at all, but just the regular >> caching? > >I certainly hope that is the case, but until I try it on the >production machine tonight I won't know for sure.
Note that not all kernels have the 'drop_caches' control file. So there is not much you can do there. >If this is indeed a >leak, it's pretty slow, and it takes a week or so before you can even >start noticing it on the graphs Well if it helps, you can accelerate the 'problem', by issuing, for example: (1) dd_rescue /dev/sda /dev/null -m $[4*1048576*1024] for reading 4 GB from disk straight and populating 'buffers'. (2) cat /some/big/big/big/file >/dev/null for reading X GB from disk and populating 'cache'. and then you'll see. Also note that a kernel leak will eventually lead to very low buffers/cached values (the ones to the far right) even when large amounts of data are read (using either dd_rescue/cat as mentioned above), because, of course, the leak clogs up memory. total used free shared buffers cached Mem: 775792 493724 282068 0 8 308416 -/+ buffers/cache: 185300 590492 Swap: 795136 60 795076 >I can say with absolute certainty that something very similar was >happening in 2.6.12 (compare the graphs in my original email), and in >2.6.12 it would inevitably lead to the server running entirely out of >memory, to the point where applications could no longer allocate >memory and the server would have to be rebooted. >The symptoms were almost identical in that case: I'd shut down >virtually every application on the server, but the memory would still >be almost entirely in use. I understand there's kernel caching, but if >the kernel caching occurs at the expense of any other applications >being able to access memory, then there's a real problem. (I actually >still have one 2.6.12 machine running, but drop_caches doesn't appear >to exist on it so I can't test it there. Is there an analogue?) If you see an Out Of Memory notice in dmesg, you'll know there is a leak even if everything was shut down. > >Anyway, I'll post the results from the 2.6.20 server as soon as I have >them. Should be late tonight. > >Thanks. > Jan -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/