From: Sergei Shtylyov <sshtylyov@ru•mvista.com>
To: mingo@elte•hu, Thomas Gleixner <tglx@linutronix•de>
Cc: linuxppc-dev@ozlabs•org
Subject: Re: Fwd: [PATCH] 2.6.18-rt7: fix more issues with 32-bit cycles_t in latency_trace.c
Date: Thu, 12 Jul 2007 21:06:27 +0400 [thread overview]
Message-ID: <46965F93.2090806@ru.mvista.com> (raw)
In-Reply-To: <200611130026.17204.sshtylyov@ru.mvista.com>
Hello, I wrote:
> In addition to clock wrap check being falsely triggered with 32-bit cycles_t,
> as noticed to Kevin Hilman, there's another issue: using %Lx format to print
> 32-bit values warrants erroneous values on 32-bit machines like ARM and PPC32.
> Signed-off-by: Sergei Shtylyov <sshtylyov@ru•mvista.com>
> ---
> PPC32 actually has 64-bit timebase counter, so could provide for 64-bit
> cycles_t -- maybe it's worth to rewrite get_cycles() to read both lower and
> upper registers?
This one (called latency-tracer-prink-fix.patch in the broken out
patchset) has been erroneously "restored" some months ago. Since
preempt_max_latency is of type 'unsigned long' now and all the other vars are
of type 'cycle_t' (which aliases 'u64'), only the first cast is actually
needed (or rather, the first format specifier needs to be changed to %08lx).
Erm, maybe I'll cook a patch...
> Index: linux-2.6/kernel/latency_trace.c
> ===================================================================
> --- linux-2.6.orig/kernel/latency_trace.c
> +++ linux-2.6/kernel/latency_trace.c
> @@ -1623,8 +1623,8 @@ check_critical_timing(int cpu, struct cp
> #ifndef CONFIG_CRITICAL_LATENCY_HIST
> if (!preempt_thresh && preempt_max_latency > delta) {
> printk("bug: updating %016Lx > %016Lx?\n",
> - preempt_max_latency, delta);
> - printk(" [%016Lx %016Lx %016Lx]\n", T0, T1, T2);
> + (u64)preempt_max_latency, (u64)delta);
> + printk(" [%016Lx %016Lx %016Lx]\n", (u64)T0, (u64)T1, (u64)T2);
> }
> #endif
WBR, Sergei
prev parent reply other threads:[~2007-07-12 17:04 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-11-12 21:26 Fwd: [PATCH] 2.6.18-rt7: fix more issues with 32-bit cycles_t in latency_trace.c Sergei Shtylyov
2007-07-12 17:06 ` Sergei Shtylyov [this message]
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