From 1bd858a507937cef6e8ca5efc6820a5744e73683 Mon Sep 17 00:00:00 2001 From: Anil S Keshavamurthy Date: Mon, 26 Jun 2006 00:25:25 -0700 Subject: [PATCH] Notify page fault call chain for x86_64 Currently in the do_page_fault() code path, we call notify_die(DIE_PAGE_FAULT, ...) to notify the page fault. Since notify_die() is highly overloaded, this page fault notification is currently being sent to all the components registered with register_die_notification() which uses the same die_chain to loop for all the registered components which is unnecessary. In order to optimize the do_page_fault() code path, this critical page fault notification is now moved to different call chain and the test results showed great improvements. And the kprobes which is interested in this notifications, now registers onto this new call chain only when it need to, i.e Kprobes now registers for page fault notification only when their are an active probes and unregisters from this page fault notification when no probes are active. I have incorporated all the feedback given by Ananth and Keith and everyone, and thanks for all the review feedback. This patch: Overloading of page fault notification with the notify_die() has performance issues(since the only interested components for page fault is kprobes and/or kdb) and hence this patch introduces the new notifier call chain exclusively for page fault notifications their by avoiding notifying unnecessary components in the do_page_fault() code path. Signed-off-by: Anil S Keshavamurthy Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/asm-x86_64/kdebug.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/asm-x86_64') diff --git a/include/asm-x86_64/kdebug.h b/include/asm-x86_64/kdebug.h index cf795631d9b4..cd52c7f33bca 100644 --- a/include/asm-x86_64/kdebug.h +++ b/include/asm-x86_64/kdebug.h @@ -15,6 +15,8 @@ struct die_args { extern int register_die_notifier(struct notifier_block *); extern int unregister_die_notifier(struct notifier_block *); +extern int register_page_fault_notifier(struct notifier_block *); +extern int unregister_page_fault_notifier(struct notifier_block *); extern struct atomic_notifier_head die_chain; /* Grossly misnamed. */ -- cgit v1.2.2