Messages in this thread | | | Date | Fri, 21 Jan 2011 14:57:46 +0100 (CET) | From | Thomas Gleixner <> | Subject | Re: [PATCH] RFC: abstract access to xtime_lock into a set of inline functions |
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On Thu, 20 Jan 2011, john stultz wrote:
> On Thu, Jan 20, 2011 at 9:30 AM, Christoph Hellwig <hch@infradead.org> wrote: > > On Thu, Jan 20, 2011 at 06:14:08PM +0100, Torben Hohn wrote: > >> the -rt patches change the xtime_lock to a raw_seqlock_t > >> so a pretty huge portion of the patch deals with changing > >> the locking functions. > >> > >> this commit uses inline functions, to hide the type > >> of the lock. > > > > That's not how kernel code usually works. > > Yea, I'm not a fan of this patch either. > > > >> - write_seqlock(&xtime_lock); > >> + xtime_write_seqlock(); > >> do_timer(1); > >> - write_sequnlock(&xtime_lock); > >> + xtime_write_sequnlock(); > > > > However there's a pretty clear pattern of taking xtime_lock, calling > > do_timer and then releasing. A useful thing you could do is to rename > > do_timer to do_timer_locked and make do_timer take and release > > xtime_lock in one place. > > Seems like a reasonable suggestion. I suspect there's still quite a > bit of stuff done under the same lock right around do_timer on a
I looked through the few remaining usage sites in arch/ and there is really no code inside the locked region which relies on xtime_lock, AFAICT.
> number of arches, but having a locked call would cut down on how > widely xtime is used.
I'd suggest to move do_timer() to kernel/time/timekeeping.c, then add xtime_update() which takes xtime_lock and calls do_timer(). After that convert each arch with a separate patch. The last step makes xtime_lock and do_timer() local to the timekeeping / clockevents code.
Thanks,
tglx | |