Subject: Re: [RFC][PATCH] perf: sysfs type id
From: Peter Zijlstra <peterz@infradead.org>
To: Stephane Eranian <eranian@google.com>
Cc: LKML <linux-kernel@vger.kernel.org>, Ingo Molnar <mingo@elte.hu>,
        Lin Ming <ming.m.lin@intel.com>,
        "robert.richter" <robert.richter@amd.com>,
        Corey Ashford <cjashfor@linux.vnet.ibm.com>,
        fweisbec <fweisbec@gmail.com>, paulus <paulus@samba.org>,
        Greg Kroah-Hartman <gregkh@suse.de>,
        Kay Sievers <kay.sievers@vrfy.org>, "H. Peter Anvin" <hpa@zytor.com>
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Date: Wed, 10 Nov 2010 15:10:07 +0100
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On Wed, 2010-11-10 at 14:01 +0100, Stephane Eranian wrote:
> Peter,

> > 6
> 
> And then, what do you do with 6?
> I assume you have to pass it in the attr struct.

perf_event_attr::type, as said in the initial changelog.

> How do you plan on doing this while keeping what is already there?

+       if (type < 0) {
+               err = idr_get_new_above(&pmu_idr, pmu, PERF_TYPE_MAX, &type);

and

+       rcu_read_lock();
+       pmu = idr_find(&pmu_idr, event->attr.type);
+       rcu_read_unlock();
+       if (pmu)
+               goto unlock;


So we start dynamic IDs at the top of the static range, and only do
dynamic IDs for those that don't already have a static number.


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