On Tue, 08 Jul 2014 13:44:04 +0900 Gioh Kim <gioh.kim@xxxxxxx> wrote: > 2014-07-08 ______ 7:52, Andrew Morton ___ ___: > > On Fri, 04 Jul 2014 17:25:09 +0900 Gioh Kim <gioh.kim@xxxxxxx> wrote: > > > >> From: Gioh Kim <gioh.kim@xxxxxxx> > >> Date: Fri, 4 Jul 2014 16:53:22 +0900 > >> Subject: [PATCH] [RFC] CMA: clear buffer-head lru before page migration > >> > >> When CMA try to migrate page, some buffer-heads can exist on lru. > >> The bh on lru has non-zero count value so that it cannot be dropped > >> even-if it is not used. We can drop only buffers related to the > >> migrated page, but it can take long time more than dropping all > >> because of searching list. There all buffers in lru are dropped. > >> > >> Signed-off-by: Laura Abbott <lauraa@xxxxxxxxxxxxxx> > >> Signed-off-by: Gioh Kim <gioh.kim@xxxxxxx> > >> --- > >> fs/buffer.c | 13 +++++++++++++ > >> 1 file changed, 13 insertions(+) > >> > >> diff --git a/fs/buffer.c b/fs/buffer.c > >> index eba6e4f..4f11b7a 100644 > >> --- a/fs/buffer.c > >> +++ b/fs/buffer.c > >> @@ -3233,6 +3233,19 @@ int try_to_free_buffers(struct page *page) > >> if (PageWriteback(page)) > >> return 0; > >> > >> +#ifdef CONFIG_CMA > >> + /* > >> + * When CMA try to migrate page, some buffer-heads can exist on lru. > >> + * The bh on lru has non-zero count value so that it cannot > >> + * be dropped even-if it is not used. > >> + * We can drop only buffers related to the migrated page, > >> + * but it can take long time more than dropping all > >> + * because of searching list. > >> + * There all buffers in lru are dropped first. > >> + */ > >> + invalidate_bh_lrus(); > >> +#endif > > > > No, this will be tremendously expensive. > > > > What I proposed is that CMA call invalidate_bh_lrus() right at the > > outset. Something along the lines of Please do not top-post your email replies - it makes it very hard to conduct a coherent discussion. > It's my fault. > I'm going to send another patch ASAP. No, not "ASAP". Such a patch will require careful testing on numerous system configurations and workloads. Take however much time it needs to get it right. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
