From mboxrd@z Thu Jan 1 00:00:00 1970 From: leon.woestenberg@gmail.com (Leon Woestenberg) Date: Sat, 17 Jan 2009 17:50:59 +0100 Subject: [ltt-dev] [RFC PATCH] block: Fix bio merge induced high I/O latency In-Reply-To: <20090117162657.GA31965@Krystal> References: <20090117004439.GA11492@Krystal> <20090117162657.GA31965@Krystal> Message-ID: Hello Mathieu et al, On Sat, Jan 17, 2009 at 5:26 PM, Mathieu Desnoyers wrote: > A long standing I/O regression (since 2.6.18, still there today) has hit > Slashdot recently : > http://bugzilla.kernel.org/show_bug.cgi?id=12309 Are you sure you are solving the *actual* problem? The bugzilla entry shows a bisect attempt that leads to a patch involving negative clock jumps. http://bugzilla.kernel.org/show_bug.cgi?id=12309#c29 with a corrected link to the bisect patch: http://bugzilla.kernel.org/show_bug.cgi?id=12309#c30 Wouldn't a negative clock jump be very influential to the (time-driven) I/O schedulers and be a more probable cause? Regards, -- Leon p.s. Added Thomas to the CC list as his name is on the patch Signed-off-by list.