From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761201AbZCYMJQ (ORCPT ); Wed, 25 Mar 2009 08:09:16 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1760925AbZCYMID (ORCPT ); Wed, 25 Mar 2009 08:08:03 -0400 Received: from hera.kernel.org ([140.211.167.34]:57139 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760936AbZCYMIA (ORCPT ); Wed, 25 Mar 2009 08:08:00 -0400 Date: Wed, 25 Mar 2009 12:06:27 GMT From: Peter Zijlstra To: linux-tip-commits@vger.kernel.org Cc: linux-kernel@vger.kernel.org, paulus@samba.org, hpa@zytor.com, mingo@redhat.com, a.p.zijlstra@chello.nl, efault@gmx.de, arjan@infradead.org, tglx@linutronix.de, fengguang.wu@intel.com, mingo@elte.hu Reply-To: arjan@infradead.org, mingo@redhat.com, hpa@zytor.com, paulus@samba.org, linux-kernel@vger.kernel.org, a.p.zijlstra@chello.nl, efault@gmx.de, tglx@linutronix.de, fengguang.wu@intel.com, mingo@elte.hu In-Reply-To: <20090325113316.740550870@chello.nl> References: <20090325113316.740550870@chello.nl> Subject: [tip:perfcounters/core] perf_counter: more elaborate write API Message-ID: Git-Commit-ID: c3f81c52021ae1c90c2718aba5114fbd54db20ff X-Mailer: tip-git-log-daemon MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.0 (hera.kernel.org [127.0.0.1]); Wed, 25 Mar 2009 12:06:29 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: c3f81c52021ae1c90c2718aba5114fbd54db20ff Gitweb: http://git.kernel.org/tip/c3f81c52021ae1c90c2718aba5114fbd54db20ff Author: Peter Zijlstra AuthorDate: Wed, 25 Mar 2009 12:30:22 +0100 Committer: Ingo Molnar CommitDate: Wed, 25 Mar 2009 13:02:51 +0100 perf_counter: more elaborate write API Provide a begin, copy, end interface to the output buffer. begin() reserves the space, copy() copies the data over, considering page boundaries, end() finalizes the event and does the wakeup. Signed-off-by: Peter Zijlstra Cc: Paul Mackerras Cc: Mike Galbraith Cc: Arjan van de Ven Cc: Wu Fengguang LKML-Reference: <20090325113316.740550870@chello.nl> Signed-off-by: Ingo Molnar --- kernel/perf_counter.c | 109 +++++++++++++++++++++++++++++++++--------------- 1 files changed, 75 insertions(+), 34 deletions(-) diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c index affe227..0422fd9 100644 --- a/kernel/perf_counter.c +++ b/kernel/perf_counter.c @@ -9,6 +9,7 @@ */ #include +#include #include #include #include @@ -16,15 +17,14 @@ #include #include #include +#include +#include +#include #include #include #include #include #include -#include -#include -#include -#include #include @@ -1411,16 +1411,20 @@ static const struct file_operations perf_fops = { * Output */ -static int perf_output_write(struct perf_counter *counter, int nmi, - void *buf, ssize_t size) +struct perf_output_handle { + struct perf_counter *counter; + struct perf_mmap_data *data; + unsigned int offset; + int wakeup; +}; + +static int perf_output_begin(struct perf_output_handle *handle, + struct perf_counter *counter, unsigned int size) { struct perf_mmap_data *data; - unsigned int offset, head, nr; - unsigned int len; - int ret, wakeup; + unsigned int offset, head; rcu_read_lock(); - ret = -ENOSPC; data = rcu_dereference(counter->data); if (!data) goto out; @@ -1428,45 +1432,82 @@ static int perf_output_write(struct perf_counter *counter, int nmi, if (!data->nr_pages) goto out; - ret = -EINVAL; - if (size > PAGE_SIZE) - goto out; - do { offset = head = atomic_read(&data->head); head += size; } while (atomic_cmpxchg(&data->head, offset, head) != offset); - wakeup = (offset >> PAGE_SHIFT) != (head >> PAGE_SHIFT); + handle->counter = counter; + handle->data = data; + handle->offset = offset; + handle->wakeup = (offset >> PAGE_SHIFT) != (head >> PAGE_SHIFT); - nr = (offset >> PAGE_SHIFT) & (data->nr_pages - 1); - offset &= PAGE_SIZE - 1; + return 0; - len = min_t(unsigned int, PAGE_SIZE - offset, size); - memcpy(data->data_pages[nr] + offset, buf, len); - size -= len; +out: + rcu_read_unlock(); - if (size) { - nr = (nr + 1) & (data->nr_pages - 1); - memcpy(data->data_pages[nr], buf + len, size); - } + return -ENOSPC; +} - /* - * generate a poll() wakeup for every page boundary crossed - */ - if (wakeup) { - atomic_xchg(&data->wakeup, POLL_IN); - __perf_counter_update_userpage(counter, data); +static void perf_output_copy(struct perf_output_handle *handle, + void *buf, unsigned int len) +{ + unsigned int pages_mask; + unsigned int offset; + unsigned int size; + void **pages; + + offset = handle->offset; + pages_mask = handle->data->nr_pages - 1; + pages = handle->data->data_pages; + + do { + unsigned int page_offset; + int nr; + + nr = (offset >> PAGE_SHIFT) & pages_mask; + page_offset = offset & (PAGE_SIZE - 1); + size = min_t(unsigned int, PAGE_SIZE - page_offset, len); + + memcpy(pages[nr] + page_offset, buf, size); + + len -= size; + buf += size; + offset += size; + } while (len); + + handle->offset = offset; +} + +static void perf_output_end(struct perf_output_handle *handle, int nmi) +{ + if (handle->wakeup) { + (void)atomic_xchg(&handle->data->wakeup, POLL_IN); + __perf_counter_update_userpage(handle->counter, handle->data); if (nmi) { - counter->wakeup_pending = 1; + handle->counter->wakeup_pending = 1; set_perf_counter_pending(); } else - wake_up(&counter->waitq); + wake_up(&handle->counter->waitq); } - ret = 0; -out: rcu_read_unlock(); +} + +static int perf_output_write(struct perf_counter *counter, int nmi, + void *buf, ssize_t size) +{ + struct perf_output_handle handle; + int ret; + ret = perf_output_begin(&handle, counter, size); + if (ret) + goto out; + + perf_output_copy(&handle, buf, size); + perf_output_end(&handle, nmi); + +out: return ret; }