From 2f5cb7381b737e24c8046fd4aeab571fb71315f5 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Tue, 7 Apr 2009 08:51:19 +0200 Subject: [PATCH] cfq-iosched: change dispatch logic to deal with single requests at the time The IO scheduler core calls into the IO scheduler dispatch_request hook to move requests from the IO scheduler and into the driver dispatch list. It only does so when the dispatch list is empty. CFQ moves several requests to the dispatch list, which can cause higher latencies if we suddenly have to switch to some important sync IO. Change the logic to move one request at the time instead. This should almost be functionally equivalent to what we did before, except that we now honor 'quantum' as the maximum queue depth at the device side from any single cfqq. If there's just a single active cfqq, we allow up to 4 times the normal quantum. Signed-off-by: Jens Axboe --- Reading git-format-patch failed