From: Andreas Schwab <schwab@suse.de>
To: linux-ia64@vger.kernel.org
Subject: Re: [RFC][PATCH] fsys_gettimeofday leaps days if it runs with nojitter
Date: Thu, 05 Jul 2007 08:48:54 +0000 [thread overview]
Message-ID: <je644zkzgp.fsf@sykes.suse.de> (raw)
In-Reply-To: <468CA2D6.40204@jp.fujitsu.com>
Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com> writes:
> I suspected the value of r28.
> So I just relocate "consuming" of r28 to early stage.
>
> <PATCH>
>> Index: linux-2.6.21/arch/ia64/kernel/fsys.S
>> =================================>> --- linux-2.6.21.orig/arch/ia64/kernel/fsys.S
>> +++ linux-2.6.21/arch/ia64/kernel/fsys.S
>> @@ -247,6 +247,9 @@
>> .time_redo:
>> .pred.rel.mutex p8,p9,p10
>> ld4.acq r28 = [r29] // xtime_lock.sequence. Must come first for locking purposes
>> + ;;
>> + and r28 = ~1,r28 // Make sequence even to force retry if odd
>> + ;;
>> (p8) mov r2 = ar.itc // CPU_TIMER. 36 clocks latency!!!
>> add r22 = IA64_TIME_INTERPOLATOR_LAST_COUNTER_OFFSET,r20
>> (p9) ld8 r2 = [r30] // readq(ti->address). Could also have latency issues..
>> @@ -284,7 +287,6 @@
>> (p15) ld8 r17 = [r19],-IA64_TIMESPEC_TV_NSEC_OFFSET
>> (p7) cmp.ne p7,p0 = r25,r3 // if cmpxchg not successful redo
>> // simulate tbit.nz.or p7,p0 = r28,0
>> - and r28 = ~1,r28 // Make sequence even to force retry if odd
>> getf.sig r2 = f8
>> mf
>> add r8 = r8,r18 // Add time interpolator offset
> </PATCH>
>
> What a surprise! This patch solves the problem!
How can the register lose its contents? The only thing that can make a
difference is the stop bit.
Andreas.
--
Andreas Schwab, SuSE Labs, schwab@suse.de
SuSE Linux Products GmbH, Maxfeldstraße 5, 90409 Nürnberg, Germany
PGP key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5
"And now for something completely different."
next prev parent reply other threads:[~2007-07-05 8:48 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-07-05 7:50 [RFC][PATCH] fsys_gettimeofday leaps days if it runs with nojitter Hidetoshi Seto
2007-07-05 8:48 ` Andreas Schwab [this message]
2007-07-05 8:57 ` Hidetoshi Seto
2007-07-10 22:20 ` Luck, Tony
2007-07-11 1:31 ` Hidetoshi Seto
2007-07-12 22:33 ` Luck, Tony
2007-07-13 1:27 ` Hidetoshi Seto
2007-07-13 9:49 ` Bob Picco
2007-07-13 23:25 ` Luck, Tony
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