Re: PATCH] fix potential latency issues in JBD's journal code

From: Theodore Tso
Date: Sat Jul 05 2008 - 10:14:53 EST


Acked-by: "Theodore Ts'o" <tytso@xxxxxxx>

I will make the corresponding change for ext4. Is the "Properly
notify block layer of sync writes" going to be pushed to mainline? I
can't add SWRITE_SYNC to the ext4 tree without growing a dependency to
this patch.

> This patch modifies two key places that submit IO that then immediately will
> get waited on. The JBD code is slightly convoluted, but after some chasing of
> abstraction layers, these instances seem to really be of this pattern.
> There's one case in checkpoint.c which is another candidate, but I've not
> been able to get my head around the code enough to verify that that one
> really is of this pattern as well, so for now I'll leave that one as is.

You mean the ll_rw_block() SWRITE in __flush_patch? Yep, seems to be
of the same pattern.

- Ted

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