There's something in your question I don't understand: If a process has 1gb in virtual memory, of which 500mb in physical, then this means that it has 500mb in swap. Or in other words: 500mb that the process wanted in physical but couldn't. (isn't that what you asked to know)
Obviously I'm missing something here. Anyway, few notes: - MM starts swapping *EVEN BEFORE* all processes hog the whole physical memory. That's because the kernel wants to leave some memory space for buffers/cache. So you may find yourself swapping idle pages while theoretically some physical memory might be freed. This behavior tunable via /proc/sys/vm/swappiness - "free" command has an interesting 2nd line, which shows the net memory usage (i.e. without buffers/cache) - The amazing "top" command can add a swap column; press "O", then "p" and enter. (If 'top' can do it, the per-process swap-vs.-physical data can probably be fetched from /proc/ some way, I don't know how, though) On Tuesday 18 December 2007 02:36, Oded Arbel wrote: > Hi List. > > I heard (but haven't actually seen) that in MS-Windows the system keeps > track of some notion of "working set", which is supposedly (if I > understand correctly) the total size of pages that an application > referenced recently - whether these are currently resident or swapped > out (see http://msdn2.microsoft.com/en-us/library/ms684891.aspx which is > an MSDN article I found on the subject). > > The way I understand processes normally work (in Linux anyway) is that > as long as there is enough memory available the memory manager keeps all > pages that an application constantly references in physical RAM, and > pages that are not references are swapped out after a while. A good > example of such is a long running Java virtual machine process (at least > the Sun implementation anyway) that doesn't return unused memory to the > operating system letting it being swapped out until its needed again - > so I have some jvm process which takes up some 1.5GB of virtual but less > then 150MB resident: it was processing a lot of data some time in the > past but now its idling. > > Now (again - according to my understanding) under contention - i.e. when > processes need to use more physical memory then what is available - the > memory manager keeps swapping stuff in and out of memory in an attempt > to satisfy all requests. Under such conditions its might be useful to > know - for each process - the amount of physical memory in use, the > amount of virtual mapped to the process, but also how much of that > virtual memory the process actually tries to use but can't get it all in > physical RAM because other processes are also hogging the memory. Does > such a thing exist in Linux? > > Thanks in advance > > -- > Oded > > > ================================================================= > To unsubscribe, send mail to [EMAIL PROTECTED] with > the word "unsubscribe" in the message body, e.g., run the command > echo unsubscribe | mail [EMAIL PROTECTED] ================================================================= To unsubscribe, send mail to [EMAIL PROTECTED] with the word "unsubscribe" in the message body, e.g., run the command echo unsubscribe | mail [EMAIL PROTECTED]
