Performance tweak: when we truncate a file but encounter pages which are still
being journaled from a previous transaction, we can't evict the page from
memory immediately.
This patch just makes it a little easier for the VM to evict the page later on:
the page is marked unreferenced while we're committing the transaction which
pins it, and the commit logic tries to free the page completely once the
transaction has committed.
--- linux-2.4-ext3merge/fs/jbd/commit.c.=K0002=.orig Thu Sep 26 12:19:14 2002
+++ linux-2.4-ext3merge/fs/jbd/commit.c Thu Sep 26 12:25:37 2002
@@ -683,13 +683,25 @@
JBUFFER_TRACE(jh, "refile for checkpoint writeback");
__journal_refile_buffer(jh);
} else {
+ struct page *page = bh->b_page;
+
J_ASSERT_BH(bh, !buffer_dirty(bh));
J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
__journal_unfile_buffer(jh);
jh->b_transaction = 0;
__journal_remove_journal_head(bh);
- __brelse(bh);
+
+ if (TryLockPage(page)) {
+ __brelse(bh);
+ } else {
+ __brelse(bh);
+ page_cache_get(page);
+ try_to_free_buffers(page, 0);
+ unlock_page(page);
+ page_cache_release(page);
+ }
}
+
spin_unlock(&journal_datalist_lock);
}
--- linux-2.4-ext3merge/fs/jbd/transaction.c.=K0002=.orig Thu Sep 26 12:19:14 2002
+++ linux-2.4-ext3merge/fs/jbd/transaction.c Thu Sep 26 12:25:37 2002
@@ -1903,8 +1903,17 @@
unlock_journal(journal);
if (!offset) {
- if (!may_free || !try_to_free_buffers(page, 0))
+ if (!may_free || !try_to_free_buffers(page, 0)) {
+ if (!offset) {
+ /* We are still using the page, but only
+ because a transaction is pinning the
+ page. Once it commits, we want to
+ encourage the page to be reaped as
+ quickly as possible. */
+ ClearPageReferenced(page);
+ }
return 0;
+ }
J_ASSERT(page->buffers == NULL);
}
return 1;
How extensively has this one been tested?
At first I prefer leaving this one for 2.4.21-pre.