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Message-ID: <ial40e$jpj$1@dough.gmane.org> Date: Mon, 1 Nov 2010 01:09:34 +0000 (UTC) From: Dimitrios Apostolou <jimis@....net> To: linux-kernel@...r.kernel.org Cc: linux-mm@...ck.org Subject: Re: 2.6.36 io bring the system to its knees Hello, On Sun, 31 Oct 2010 09:51:32 +0800, Wu Fengguang wrote: > It may also help to lower the dirty ratio. > > echo 5 > /proc/sys/vm/dirty_ratio > > Memory pressure + heavy write can easily hurt responsiveness. > > - eats up to 20% (the default value for dirty_ratio) memory with dirty > pages and hence increase the memory pressure and number of swap IO My experience has been different with that. Wouldn't it make more sense to _increase_ dirty_ratio (to 50 lets say) and at the same time decrease dirty_background_ratio? That way writing to disk starts early, but the related apps stall waiting for I/O only when dirty_ratio is reached. Thanks, Dimitris > > - the file copy makes the device write congested and hence makes > pageout() easily blocked in get_request_wait() > > As a result every application may be slowed down by the heavy swap IO > when page fault as well as being blocked when allocating memory (which > may go into direct reclaim and then call pageout()). > > Thanks, > Fengguang -- 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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