Hi Jan, On 11/07/2013 07:44 PM, Jan Kara wrote: > On Tue 05-11-13 18:02:03, Gu Zheng wrote: >> Stop the loop of iterating bh if we have confirmed page >> has dirty and writeback buffers. > Thanks for the patch. What I'm somewhat missing here is a motivation of > the patch. For the common case where blocksize == pagesize this is a noop > (only adds some code). Yes, you're right. > For the case where blocksize < pagesize we can > possibly save checking some buffers but how common is that going be? It's really hard to say.:( But many file systems support small blocksize. > Does that minimal speed up outweight the cost of additional check / code > complication? In fact, without complete test. But I think the speed up can outweigh the cost if blocksize small enough. For example, blocksize: 1k, pagesize: 4k, we can reduce 6 bh check(3 dirty, 3 writeback) in the best case. Best regards, Gu > > Honza > >> >> Signed-off-by: Gu Zheng <guz.fnst@xxxxxxxxxxxxxx> >> --- >> fs/buffer.c | 2 +- >> 1 files changed, 1 insertions(+), 1 deletions(-) >> >> diff --git a/fs/buffer.c b/fs/buffer.c >> index 6024877..519cc5c 100644 >> --- a/fs/buffer.c >> +++ b/fs/buffer.c >> @@ -112,7 +112,7 @@ void buffer_check_dirty_writeback(struct page *page, >> *dirty = true; >> >> bh = bh->b_this_page; >> - } while (bh != head); >> + } while ((bh != head) && !(*writeback && *dirty)); >> } >> EXPORT_SYMBOL(buffer_check_dirty_writeback); >> >> -- >> 1.7.7 >> >> -- >> 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 -- 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
