Re: Disk write cache (Was: Hyper-Threading Vulnerability)

[Jeff Garzik <jgarzik@pobox.com>]

Gene Heskett wrote:
> I don't think I have any drives here that do obey that, Jeff.  I got 
> curious about this, oh, maybe a year back when this discussion first 
> took place on another list, and wrote a test gizmo that copied a 
> large file, then slept for 1 second and issued a sync command.  No 
> drive led activity until the usual 5 second delay of the filesystem 
> had expired.  To me, that indicated that the sync command was being 
> returned as completed without error and I had my shell prompt back 
> long before the drives leds came on.  Admittedly that may not be a 
> 100% valid test, but I really did expect to see the leds come on as 
> the sync command was executed.

> Again, probably not a valid test of the sync command, but thats the 
> evidence I have.  I do not believe it works here, with any of the 5 
> drives currently spinning in these two boxes.

Correct, that's a pretty poor test.

	Jeff


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