On Mon, Sep 13, 2010 at 11:21:16AM +0800, Neil Brown wrote: > On Mon, 13 Sep 2010 09:55:29 +0800 > Wu Fengguang <fengguang.wu@xxxxxxxxx> wrote: > > > On Mon, Sep 13, 2010 at 04:46:54AM +0800, Neil Brown wrote: > > > On Sun, 12 Sep 2010 23:49:50 +0800 > > > Wu Fengguang <fengguang.wu@xxxxxxxxx> wrote: > > > > > > > This allows quick response to Ctrl-C etc. for impatient users. > > > > > > > > Signed-off-by: Wu Fengguang <fengguang.wu@xxxxxxxxx> > > > > --- > > > > mm/page-writeback.c | 3 +++ > > > > 1 file changed, 3 insertions(+) > > > > > > > > --- linux-next.orig/mm/page-writeback.c 2010-09-09 16:01:14.000000000 +0800 > > > > +++ linux-next/mm/page-writeback.c 2010-09-09 16:02:27.000000000 +0800 > > > > @@ -553,6 +553,9 @@ static void balance_dirty_pages(struct a > > > > __set_current_state(TASK_INTERRUPTIBLE); > > > > io_schedule_timeout(pause); > > > > > > > > + if (signal_pending(current)) > > > > + break; > > > > + > > > > > > Given the patch description, I think you might want "fatal_signal_pending()" > > > here ??? > > > > __fatal_signal_pending() tests SIGKILL only, while the one often used > > and need more quick responding is SIGINT.. > > > > I thought that at first too.... but I don't think that is the case. > > In kernel/signal.c, in complete_signal, we have > if (sig_fatal() ...) > .... > sigaddset(&t->pending.signal, SIGKILL); > > where sig_fatal is > > #define sig_fatal(t, signr) \ > (!siginmask(signr, SIG_KERNEL_IGNORE_MASK|SIG_KERNEL_STOP_MASK) && \ > (t)->sighand->action[(signr)-1].sa.sa_handler == SIG_DFL) > > > so (if I'm reading the code correctly), if a process receives a signal for > which the handler is SIG_DFL, then SIGKILL is set in the pending mask, so > __fatal_signal_pending will be true. > > So it fatal_signal_pending should catch any signal that will cause the > process to exit. I assume that it what you want... Ah yes, it does look so. Thanks for the detailed explanation! Here is the updated patch. Thanks, Fengguang --- Subject: writeback: quit throttling when fatal signal pending From: Wu Fengguang <fengguang.wu@xxxxxxxxx> Date: Wed Sep 08 17:40:22 CST 2010 This allows quick response to Ctrl-C etc. for impatient users. It mainly helps the rare bdi/global dirty exceeded cases. In the normal case of not exceeded, it will quit the loop anyway. CC: Neil Brown <neilb@xxxxxxx> Signed-off-by: Wu Fengguang <fengguang.wu@xxxxxxxxx> --- mm/page-writeback.c | 3 +++ 1 file changed, 3 insertions(+) --- linux-next.orig/mm/page-writeback.c 2010-09-12 13:25:23.000000000 +0800 +++ linux-next/mm/page-writeback.c 2010-09-13 11:39:33.000000000 +0800 @@ -552,6 +552,9 @@ static void balance_dirty_pages(struct a __set_current_state(TASK_INTERRUPTIBLE); io_schedule_timeout(pause); + if (fatal_signal_pending(current)) + break; + check_exceeded: /* * The bdi thresh is somehow "soft" limit derived from the -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>