From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932552Ab3KFNYa (ORCPT ); Wed, 6 Nov 2013 08:24:30 -0500 Received: from terminus.zytor.com ([198.137.202.10]:48929 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932158Ab3KFNUM (ORCPT ); Wed, 6 Nov 2013 08:20:12 -0500 Date: Wed, 6 Nov 2013 05:19:05 -0800 From: tip-bot for Peter Zijlstra Message-ID: Cc: linux-kernel@vger.kernel.org, anton@samba.org, mathieu.desnoyers@polymtl.ca, hpa@zytor.com, mingo@kernel.org, michael@ellerman.id.au, peterz@infradead.org, vince@deater.net, paulmck@linux.vnet.ibm.com, benh@kernel.crashing.org, fweisbec@gmail.com, oleg@redhat.com, VICTORK@il.ibm.com, tglx@linutronix.de, mikey@neuling.org Reply-To: mingo@kernel.org, hpa@zytor.com, mathieu.desnoyers@polymtl.ca, anton@samba.org, linux-kernel@vger.kernel.org, peterz@infradead.org, michael@ellerman.id.au, paulmck@linux.vnet.ibm.com, vince@deater.net, fweisbec@gmail.com, benh@kernel.crashing.org, tglx@linutronix.de, VICTORK@il.ibm.com, oleg@redhat.com, mikey@neuling.org To: linux-tip-commits@vger.kernel.org Subject: [tip:perf/core] perf: Optimize perf_output_begin() -- address calculation Git-Commit-ID: 524feca5e9da9e5f9e5aa5d5613b1d762db9509e X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.1 (terminus.zytor.com [127.0.0.1]); Wed, 06 Nov 2013 05:19:11 -0800 (PST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 524feca5e9da9e5f9e5aa5d5613b1d762db9509e Gitweb: http://git.kernel.org/tip/524feca5e9da9e5f9e5aa5d5613b1d762db9509e Author: Peter Zijlstra AuthorDate: Thu, 31 Oct 2013 17:36:25 +0100 Committer: Ingo Molnar CommitDate: Wed, 6 Nov 2013 12:34:22 +0100 perf: Optimize perf_output_begin() -- address calculation Rewrite the handle address calculation code to be clearer. Saves 8 bytes on x86_64-defconfig. Signed-off-by: Peter Zijlstra Cc: Benjamin Herrenschmidt Cc: Frederic Weisbecker Cc: Mathieu Desnoyers Cc: Michael Ellerman Cc: Michael Neuling Cc: "Paul E. McKenney" Cc: james.hogan@imgtec.com Cc: Vince Weaver Cc: Victor Kaplansky Cc: Oleg Nesterov Cc: Anton Blanchard Link: http://lkml.kernel.org/n/tip-3trb2n2henb9m27tncef3ag7@git.kernel.org Signed-off-by: Ingo Molnar --- kernel/events/ring_buffer.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c index e4d70f3..c52a32f 100644 --- a/kernel/events/ring_buffer.c +++ b/kernel/events/ring_buffer.c @@ -105,7 +105,7 @@ int perf_output_begin(struct perf_output_handle *handle, { struct ring_buffer *rb; unsigned long tail, offset, head; - int have_lost; + int have_lost, page_shift; struct { struct perf_event_header header; u64 id; @@ -159,12 +159,12 @@ int perf_output_begin(struct perf_output_handle *handle, if (unlikely(head - local_read(&rb->wakeup) > rb->watermark)) local_add(rb->watermark, &rb->wakeup); - handle->page = offset >> (PAGE_SHIFT + page_order(rb)); - handle->page &= rb->nr_pages - 1; - handle->size = offset & ((PAGE_SIZE << page_order(rb)) - 1); - handle->addr = rb->data_pages[handle->page]; - handle->addr += handle->size; - handle->size = (PAGE_SIZE << page_order(rb)) - handle->size; + page_shift = PAGE_SHIFT + page_order(rb); + + handle->page = (offset >> page_shift) & (rb->nr_pages - 1); + offset &= (1UL << page_shift) - 1; + handle->addr = rb->data_pages[handle->page] + offset; + handle->size = (1UL << page_shift) - offset; if (unlikely(have_lost)) { struct perf_sample_data sample_data;