Messages in this thread | | | Date | Tue, 12 Feb 2002 20:29:43 -0800 | From | Andrew Morton <> | Subject | Re: [patch] sys_sync livelock fix |
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Bill Davidsen wrote: > > Alan and/or Linus: > > Am I misreading this or is the Linux implementation of sync() based on > making the shutdown scripts pause until disk i/o is done? Because I don't > think commercial unices work that way, I think they work as SuS > specifies. More reason to rethink this in 2.4 as well as 2.5 and get the > possible live lock out of the kernel. >
IMO, the SuS definition sucks. We really do want to do our best to ensure that pending writes are committed to disk before sys_sync() returns. As long as that doesn't involve waiting until mid-August.
For example, ext3 users get to enjoy rebooting with `sync ; reboot -f' to get around all those silly shutdown scripts. This very much relies upon the sync waiting upon the I/O.
I mean, according to SUS, our sys_sync() implementation could be
asmlinkage void sys_sync(void) { return; }
Because all I/O is already scheduled, thanks to kupdate.
But we want sync to be useful.
> > If this were only a performance issue I wouldn't push for prompt > implementation, but anything which can hang the system, particularly in > shutdown, is bad. >
If shutdown hangs, it's probably due to something else.
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