lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [day] [month] [year] [list]
Date:	Sun, 19 Feb 2012 12:13:18 +0100
From:	Stephane Eranian <>
To:	Paul Mackerras <>
Cc:	Anton Blanchard <>,,,,,,,,,,,,,
Subject: Re: [PATCH] powerpc: perf: power_pmu_start restores incorrect values,
 breaking frequency events

Glad to see you fixed the PPC problem.

On Thu, Feb 16, 2012 at 5:57 AM, Paul Mackerras <> wrote:
> On Thu, Feb 16, 2012 at 03:48:22PM +1100, Anton Blanchard wrote:
>> perf on POWER stopped working after commit e050e3f0a71b (perf: Fix
>> broken interrupt rate throttling). That patch exposed a bug in
>> the POWER perf_events code.
>> Since the PMCs count upwards and take an exception when the top bit
>> is set, we want to write 0x80000000 - left in power_pmu_start. We were
>> instead programming in left which effectively disables the counter
>> until we eventually hit 0x80000000. This could take seconds or longer.
>> With the patch applied I get the expected number of samples:
>> # taskset -c 0 yes > /dev/null &
>> # perf record -C 0 -a sleep 10
>> # perf report -D | grep SAMPLE | tail -1
>>           SAMPLE events:       9948
>> Signed-off-by: Anton Blanchard <>
> Acked-by: Paul Mackerras <>
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

Powered by blists - more mailing lists