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From: Boris Ostrovsky <boris.ostrovsky@oracle.com>
To: xen-devel <xen-devel@lists.xen.org>
Subject: LVTPC masking in Intel VPMU code
Date: Wed, 27 Mar 2013 17:34:23 -0400	[thread overview]
Message-ID: <515365DF.7000600@oracle.com> (raw)

Can someone explain why we have these lines in 
vpmu_core2.c:core2_vpmu_do_interrupt():
     apic_write_around(APIC_LVTPC, apic_read(APIC_LVTPC) & 
~APIC_LVT_MASKED);
     ...
     vlapic_set_reg(vlapic, APIC_LVTPC, vlapic_lvtpc | APIC_LVT_MASKED);

There is similar code in Linux oprofile with a comment that this is done 
due to some sort of
a quirk on P4 and PentiumM. Is this why it's in 
core2_vpmu_do_interrupt() as well?

I don't see a quirk like this in Linux perf code.


-boris

             reply	other threads:[~2013-03-27 21:34 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-03-27 21:34 Boris Ostrovsky [this message]
2013-03-28 11:26 ` LVTPC masking in Intel VPMU code Jan Beulich
2013-03-29  9:12   ` Shan, Haitao
  -- strict thread matches above, loose matches on Subject: below --
2013-03-29 12:39 Boris Ostrovsky
2013-04-01 20:53 ` Boris Ostrovsky
2013-04-02  1:29   ` Shan, Haitao

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