From 7602bdf2fd14a40dd9b104e516fdc05e1bd17952 Mon Sep 17 00:00:00 2001 From: Ashwin Chaugule Date: Wed, 6 Dec 2006 20:31:57 -0800 Subject: [PATCH] new scheme to preempt swap token The new swap token patches replace the current token traversal algo. The old algo had a crude timeout parameter that was used to handover the token from one task to another. This algo, transfers the token to the tasks that are in need of the token. The urgency for the token is based on the number of times a task is required to swap-in pages. Accordingly, the priority of a task is incremented if it has been badly affected due to swap-outs. To ensure that the token doesnt bounce around rapidly, the token holders are given a priority boost. The priority of tasks is also decremented, if their rate of swap-in's keeps reducing. This way, the condition to check whether to pre-empt the swap token, is a matter of comparing two task's priority fields. [akpm@osdl.org: cleanups] Signed-off-by: Ashwin Chaugule Cc: Rik van Riel Cc: Peter Zijlstra Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/sched.h | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) (limited to 'include/linux/sched.h') diff --git a/include/linux/sched.h b/include/linux/sched.h index eafe4a7b8237..cad6a16260f7 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -344,9 +344,16 @@ struct mm_struct { /* Architecture-specific MM context */ mm_context_t context; - /* Token based thrashing protection. */ - unsigned long swap_token_time; - char recent_pagein; + /* Swap token stuff */ + /* + * Last value of global fault stamp as seen by this process. + * In other words, this value gives an indication of how long + * it has been since this task got the token. + * Look at mm/thrash.c + */ + unsigned int faultstamp; + unsigned int token_priority; + unsigned int last_interval; /* coredumping support */ int core_waiters; -- cgit v1.2.3