On Tue, 7 Apr 2009 18:19:33 -0400 Theodore Tso <tytso@xxxxxxx> wrote: > Now that we have a distinction between WRITE_SYNC and WRITE_SYNC_PLUG, > use WRITE_SYNC_PLUG in __block_write_full_page() to avoid unplugging > the block device I/O queue between each page that gets flushed out. > > The upstream callers of block_write_full_page() which wait for the > writes to finish call wait_on_buffer(), wait_on_writeback_range() > (which ultimately calls sync_page(), which calls > blk_run_backing_dev(), which will unplug the device queue), and so on. > <sob> > > We should get this applied to avoid any performance regressions > resulting from commit a64c8610. > > fs/buffer.c | 3 ++- > 1 files changed, 2 insertions(+), 1 deletions(-) > > diff --git a/fs/buffer.c b/fs/buffer.c > index 977e12a..95b5390 100644 > --- a/fs/buffer.c > +++ b/fs/buffer.c > @@ -1646,7 +1646,8 @@ static int __block_write_full_page(struct inode *inode, struct page *page, > struct buffer_head *bh, *head; > const unsigned blocksize = 1 << inode->i_blkbits; > int nr_underway = 0; > - int write_op = (wbc->sync_mode == WB_SYNC_ALL ? WRITE_SYNC : WRITE); > + int write_op = (wbc->sync_mode == WB_SYNC_ALL ? > + WRITE_SYNC_PLUG : WRITE); > > BUG_ON(!PageLocked(page)); So how does WRITE_SYNC_PLUG differ from WRITE, and what effect does this change have upon kernel behaviour? -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
