Date: Wed, 24 Dec 2003 23:10:08 -0800 (PST) From: Matthew Dillon <dillon@apollo.backplane.com> To: Paul Mather <paul@gromit.dlib.vt.edu> Cc: freebsd-stable@freebsd.org Subject: Re: Problems reclaiming VM cache = XFree86 startup annoyance Message-ID: <200312250710.hBP7A8nv027004@apollo.backplane.com> References: <200312212310.KAA04764@lightning.itga.com.au> <20031225011412.GA441@gromit.dlib.vt.edu>
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:I'm not sure what is overloading the disk other than the large amounts :of paging that are initiated the moment I invoke "startx". The last :time I did this, I looked at the disk activity beforehand via "systat :-vm 1". The disks were basically idle (all < 0.05 MB/s). As soon as :I executed "startx" the swap volume became very active (90--96% busy; :3--7 MB/sec) and the "SWAP PAGER" out column steadily showed paging :activity (nothing on the "in" column). (The 4 KB/t was a tell-tale :sign the system was doing nothing but paging.) : :I guess my question is this: why so much paging? If, as someone else :has mentioned, "Cache" and "Free" pages are both "free" (i.e., :allocable memory), with the subtle distinction being that "Cache" :pages used to hold disk blocks now discarded, then why not allocate :what is needed from them? As I stated in my original thread, all the :"Inactive" memory seems to get dumped over to "Cache" when I run :"startx", and there's usually almost about 400 MB of it when this :happens. :... :Cheers, : :Paul. If it could, it would... my guess is that your box is using a shared memory video buffer and X is allocating a large swath of contiguous physical memory to accomodate it, which would force it to pageout any preexisting dirty data using that memory. That's all I can think of. -Matt Matthew Dillon <dillon@backplane.com>
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