Messages in this thread | | | Date | Tue, 12 Feb 2002 23:53:23 -0500 (EST) | From | Bill Davidsen <> | Subject | Re: [patch] sys_sync livelock fix |
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On Tue, 12 Feb 2002, Jeff Garzik wrote:
> 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. > > I don't think SuSv2 can be any more clear than: > > > The writing, although scheduled, is not necessarily complete > > upon return from sync(). > > Quoting from http://www.opengroup.org/onlinepubs/007908799/xsh/sync.html
I don't see anything which says we can't implement sync(2) as your checkpoint, as long as we don't keep the current implementation which could hang forever in theory, and for hours in practice. I don't think that violates the standard, and it should be safe.
I said before that we could make sync(2) fast and just put up a barrier to keep additional io from being queued, and I still like that. Pass on the need for checkpoint, or the portability thereof. I would expect all current programs to work if cync(2) worked like your checkpoint(2).
Glad you read the SuSv2 the same way!
-- bill davidsen <davidsen@tmr.com> CTO, TMR Associates, Inc Doing interesting things with little computers since 1979.
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