Messages in this thread | | | Subject | Re: 2.4.21-pre2 stalls out when running unixbench | From | "Stephen C. Tweedie" <> | Date | 06 Jan 2003 13:20:35 +0000 |
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Hi,
On Mon, 2003-01-06 at 12:15, John Bradford wrote:
> What!? I'm suprised that no userspace applications were broken by > sync returning before the data is safely on oxide, even though it > doesn't violate the POSIX spec.
sync(2) syncs _everything_ --- every M/O or floppy disk, every filesystem no matter if it's fat or native Unix. It's way too heavyweight for most applications which have synchronisation requirements, when fsync() or O_SYNC are much more precise.
I think I can recall one or two mutterings about people worried about theoretical risks of doing things like "lilo; sync; reboot", but that's a different class of risk altogether. (It's complicated by the problem that after a sync, ext3 guarantees that the data and metadata is on disk, but it may still be in the journal, so lilo won't necessarily see the right stuff with sync() alone --- ext3 plays extra tricks when it sees bmap to try to solve this.)
--Stephen
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