<div class="gmail_quote">On Wed, Aug 22, 2012 at 8:44 PM, Tao Ma <span dir="ltr"><<a href="mailto:tm@tao.ma" target="_blank">tm@tao.ma</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
I guess the final solution will be WRITE_FUA, and I see btrfs uses it to<br>
write out the superblock. It will be handled differently by the<br>
underlying block layer so that it will not be in the elevator queue. It<br>
should work but I am not sure whether we need to be so aggressive. Maybe<br>
some test will show.<br><br></blockquote><div><br></div><div>FUA is an overkill for the heartbeat data because we don't care if that data</div><div>hits the platter or not. It can stay in the device's volatile cache. Infact, staying</div>
<div>in the cache, and not hitting the platter, is better.</div><div><br></div></div>