From: Alexander Shishkin <alexander.shishkin@linux.intel.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>, linux-kernel@vger.kernel.org,
        Robert Richter <rric@kernel.org>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        Mike Galbraith <efault@gmx.de>, Paul Mackerras <paulus@samba.org>,
        Stephane Eranian <eranian@google.com>, Andi Kleen <ak@linux.intel.com>,
        kan.liang@intel.com, adrian.hunter@intel.com, acme@infradead.org
Subject: Re: [PATCH v5 12/20] x86: perf: intel_pt: Intel PT PMU driver
In-Reply-To: <20141022142003.GQ12706@worktop.programming.kicks-ass.net>
References: <1413207948-28202-1-git-send-email-alexander.shishkin@linux.intel.com> <1413207948-28202-13-git-send-email-alexander.shishkin@linux.intel.com> <20141022142003.GQ12706@worktop.programming.kicks-ass.net>
User-Agent: Notmuch/0.17+49~gaa57e9d (http://notmuchmail.org) Emacs/24.3.1 (x86_64-pc-linux-gnu)
Date: Fri, 24 Oct 2014 10:49:33 +0300
Message-ID: <878uk53o1e.fsf@ashishki-desk.ger.corp.intel.com>
MIME-Version: 1.0
Content-Type: text/plain
Sender: linux-kernel-owner@vger.kernel.org

Peter Zijlstra <peterz@infradead.org> writes:

> On Mon, Oct 13, 2014 at 04:45:40PM +0300, Alexander Shishkin wrote:
>> +++ b/arch/x86/kernel/cpu/perf_event_intel.c
>> @@ -1528,6 +1528,14 @@ again:
>>  	}
>>  
>>  	/*
>> +	 * Intel PT
>> +	 */
>> +	if (__test_and_clear_bit(55, (unsigned long *)&status)) {
>> +		handled++;
>> +		intel_pt_interrupt();
>> +	}
>> +
>
> How does the PT interrupt interact with the regular PMI? In particular
> does it respect stuff like FREEZE_ON_PMI etc?

It ignores the FREEZE_ON_PMI bit. I stop it by hand inside the PMI
handler, so you can see parts of the handler in the trace if you're
tracing the kernel.

Regards,
--
Alex
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/