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Date: Mon, 25 May 2009 03:39:50 GMT
From: tip-bot for Ingo Molnar <mingo@elte.hu>
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Subject: [tip:perfcounters/core] perf_counter: Increase mmap limit
Message-ID: <tip-a3862d3f814ce7dfca9eed56ac23d29db3aee8d5@git.kernel.org>
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Commit-ID:  a3862d3f814ce7dfca9eed56ac23d29db3aee8d5
Gitweb:     http://git.kernel.org/tip/a3862d3f814ce7dfca9eed56ac23d29db3aee8d5
Author:     Ingo Molnar <mingo@elte.hu>
AuthorDate: Sun, 24 May 2009 09:02:37 +0200
Committer:  Ingo Molnar <mingo@elte.hu>
CommitDate: Sun, 24 May 2009 09:02:37 +0200

perf_counter: Increase mmap limit

In a default 'perf top' run the tool will create a counter for
each online CPU. With enough CPUs this will eventually exhaust
the default limit.

So scale it up with the number of online CPUs.

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>


---
 kernel/perf_counter.c |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
index cb40625..6cdf824 100644
--- a/kernel/perf_counter.c
+++ b/kernel/perf_counter.c
@@ -1704,6 +1704,12 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma)
 
 	user_extra = nr_pages + 1;
 	user_lock_limit = sysctl_perf_counter_mlock >> (PAGE_SHIFT - 10);
+
+	/*
+	 * Increase the limit linearly with more CPUs:
+	 */
+	user_lock_limit *= num_online_cpus();
+
 	user_locked = atomic_long_read(&user->locked_vm) + user_extra;
 
 	extra = 0;