RE: Mainline kernel OLTP performance update

[Styner, Douglas W]

What we showed was that vmstat and vtune agreed wrt system/user time.  Oprofile is off by ~4% (4% too low for user. 4% too high for system)

>-----Original Message-----
>From: Andi Kleen [mailto:andi@xxxxxxxxxxxxxx]
>Sent: Wednesday, April 29, 2009 1:28 AM
>To: Andrew Morton
>Cc: Styner, Douglas W; linux-kernel@xxxxxxxxxxxxxxx; Tripathi, Sharad C;
>arjan@xxxxxxxxxxxxxxx; Wilcox, Matthew R; Kleen, Andi; Siddha, Suresh B;
>Ma, Chinang; Wang, Peter Xihong; Nueckel, Hubert; Recalde, Luis F; Nelson,
>Doug; Cheng, Wu-sun; Prickett, Terry O; Shunmuganathan, Rajalakshmi; Garg,
>Anil K; Chilukuri, Harita; chris.mason@xxxxxxxxxx
>Subject: Re: Mainline kernel OLTP performance update
>
>Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> writes:
>
>>> ======oprofile CPU_CLK_UNHALTED for top 30 functions
>>> Cycles% 2.6.24.2                   Cycles% 2.6.30-rc3
>>> 74.8578 <database>                 69.1925 <database>
>>
>> ouch, that's a large drop in userspace CPU occupancy.  It seems
>> inconsistent with the 1.91% above.
>
>That was determined to be an oprofile artifact/regression (see Doug's
>other email+thread) The 2.6.30 oprofile seems to be less accurate than
>the one in 2.6.24. Of course the question is if it can't get
>the user space right, is the kernel data accurate. But I believe
>Doug verified with vtune that the kernel data is roughly correct,
>just user space profiling was slightly bogus (right, Doug, or
>do I misrepresent that?)
>
>-Andi
>
>--
>ak@xxxxxxxxxxxxxxx -- Speaking for myself only.
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