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Date: Sun, 29 Nov 2009 17:06:26 +1100 From: Ben Nizette <bn@...sdigital.com> To: Adam Nielsen <a.nielsen@...kadi.net> Cc: LKML Mailinglist <linux-kernel@...r.kernel.org> Subject: Re: Why does the disk still thrash when I have no swap? On Sun, 2009-11-29 at 14:59 +1000, Adam Nielsen wrote: > Could it be that the disk cache was > forced to shrink and suddenly all accesses to the filesystem became unbuffered > and incredibly slow? Why would this stop the X11 mouse cursor from moving? Pretty much, yeah. Well, not so much that the filesystem became unbuffered, the new files you're accessing would have still been pulled in to RAM, but rather all the old files you were no longer accessing but were still in memory had to hit the disk before new allocations could succeed. Given the modern programmer's love of OOP, pretty much every action you can think of causes a massive number of (generally small) allocations and even though each one would likely free shortly after, could still potentially trigger a dirty page writeback before the allocation would succeed. This is one of my pet annoyances - most OOP programmers forget that object creation is potentially IO-bound in low memory situations (either by swap or by pagecache writeback) and wonder why seemingly innocuous things like "new Integer()" can take many seconds to complete! --Ben. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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