From mboxrd@z Thu Jan 1 00:00:00 1970 From: Waiman Long Subject: Re: [PATCH v2 2/4] locking/qspinlock_stat: Track the no MCS node available case Date: Wed, 23 Jan 2019 15:04:05 -0500 Message-ID: <39716536-be0b-8eba-4f56-ab6ff97447be@redhat.com> References: <1548215351-18896-1-git-send-email-longman@redhat.com> <1548215351-18896-3-git-send-email-longman@redhat.com> <20190123092339.GD15019@brain-police> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20190123092339.GD15019@brain-police> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Will Deacon Cc: Peter Zijlstra , Ingo Molnar , Thomas Gleixner , Borislav Petkov , "H. Peter Anvin" , linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, x86@kernel.org, Zhenzhong Duan , James Morse , SRINIVAS List-Id: linux-arch.vger.kernel.org On 01/23/2019 04:23 AM, Will Deacon wrote: > On Tue, Jan 22, 2019 at 10:49:09PM -0500, Waiman Long wrote: >> Track the number of slowpath locking operations that are being done >> without any MCS node available as well renaming lock_index[123] to make >> them more descriptive. >> >> Using these stat counters is one way to find out if a code path is >> being exercised. >> >> Signed-off-by: Waiman Long >> --- >> kernel/locking/qspinlock.c | 3 ++- >> kernel/locking/qspinlock_stat.h | 21 +++++++++++++++------ >> 2 files changed, 17 insertions(+), 7 deletions(-) >> >> diff --git a/kernel/locking/qspinlock.c b/kernel/locking/qspinlock.c >> index 0875053..21ee51b 100644 >> --- a/kernel/locking/qspinlock.c >> +++ b/kernel/locking/qspinlock.c >> @@ -422,6 +422,7 @@ void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val) >> * simple enough. >> */ >> if (unlikely(idx >= MAX_NODES)) { >> + qstat_inc(qstat_lock_no_node, true); >> while (!queued_spin_trylock(lock)) >> cpu_relax(); >> goto release; >> @@ -432,7 +433,7 @@ void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val) >> /* >> * Keep counts of non-zero index values: >> */ >> - qstat_inc(qstat_lock_idx1 + idx - 1, idx); >> + qstat_inc(qstat_lock_use_node2 + idx - 1, idx); >> >> /* >> * Ensure that we increment the head node->count before initialising >> diff --git a/kernel/locking/qspinlock_stat.h b/kernel/locking/qspinlock_stat.h >> index 42d3d8d..31728f6 100644 >> --- a/kernel/locking/qspinlock_stat.h >> +++ b/kernel/locking/qspinlock_stat.h >> @@ -30,6 +30,13 @@ >> * pv_wait_node - # of vCPU wait's at a non-head queue node >> * lock_pending - # of locking operations via pending code >> * lock_slowpath - # of locking operations via MCS lock queue >> + * lock_use_node2 - # of locking operations that use 2nd percpu node >> + * lock_use_node3 - # of locking operations that use 3rd percpu node >> + * lock_use_node4 - # of locking operations that use 4th percpu node >> + * lock_no_node - # of locking operations without using percpu node >> + * >> + * Subtraccting lock_use_node[234] from lock_slowpath will give you >> + * lock_use_node1. > Typo: "subtraccting" > > Will Thanks for catching that. Cheers, Longman From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:40884 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725999AbfAWUEJ (ORCPT ); Wed, 23 Jan 2019 15:04:09 -0500 Subject: Re: [PATCH v2 2/4] locking/qspinlock_stat: Track the no MCS node available case References: <1548215351-18896-1-git-send-email-longman@redhat.com> <1548215351-18896-3-git-send-email-longman@redhat.com> <20190123092339.GD15019@brain-police> From: Waiman Long Message-ID: <39716536-be0b-8eba-4f56-ab6ff97447be@redhat.com> Date: Wed, 23 Jan 2019 15:04:05 -0500 MIME-Version: 1.0 In-Reply-To: <20190123092339.GD15019@brain-police> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: linux-arch-owner@vger.kernel.org List-ID: To: Will Deacon Cc: Peter Zijlstra , Ingo Molnar , Thomas Gleixner , Borislav Petkov , "H. Peter Anvin" , linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, x86@kernel.org, Zhenzhong Duan , James Morse , SRINIVAS Message-ID: <20190123200405.CLfKdq-QKjs729LFc14kFC7E86yyOf5OgODWUqxDSJQ@z> On 01/23/2019 04:23 AM, Will Deacon wrote: > On Tue, Jan 22, 2019 at 10:49:09PM -0500, Waiman Long wrote: >> Track the number of slowpath locking operations that are being done >> without any MCS node available as well renaming lock_index[123] to make >> them more descriptive. >> >> Using these stat counters is one way to find out if a code path is >> being exercised. >> >> Signed-off-by: Waiman Long >> --- >> kernel/locking/qspinlock.c | 3 ++- >> kernel/locking/qspinlock_stat.h | 21 +++++++++++++++------ >> 2 files changed, 17 insertions(+), 7 deletions(-) >> >> diff --git a/kernel/locking/qspinlock.c b/kernel/locking/qspinlock.c >> index 0875053..21ee51b 100644 >> --- a/kernel/locking/qspinlock.c >> +++ b/kernel/locking/qspinlock.c >> @@ -422,6 +422,7 @@ void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val) >> * simple enough. >> */ >> if (unlikely(idx >= MAX_NODES)) { >> + qstat_inc(qstat_lock_no_node, true); >> while (!queued_spin_trylock(lock)) >> cpu_relax(); >> goto release; >> @@ -432,7 +433,7 @@ void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val) >> /* >> * Keep counts of non-zero index values: >> */ >> - qstat_inc(qstat_lock_idx1 + idx - 1, idx); >> + qstat_inc(qstat_lock_use_node2 + idx - 1, idx); >> >> /* >> * Ensure that we increment the head node->count before initialising >> diff --git a/kernel/locking/qspinlock_stat.h b/kernel/locking/qspinlock_stat.h >> index 42d3d8d..31728f6 100644 >> --- a/kernel/locking/qspinlock_stat.h >> +++ b/kernel/locking/qspinlock_stat.h >> @@ -30,6 +30,13 @@ >> * pv_wait_node - # of vCPU wait's at a non-head queue node >> * lock_pending - # of locking operations via pending code >> * lock_slowpath - # of locking operations via MCS lock queue >> + * lock_use_node2 - # of locking operations that use 2nd percpu node >> + * lock_use_node3 - # of locking operations that use 3rd percpu node >> + * lock_use_node4 - # of locking operations that use 4th percpu node >> + * lock_no_node - # of locking operations without using percpu node >> + * >> + * Subtraccting lock_use_node[234] from lock_slowpath will give you >> + * lock_use_node1. > Typo: "subtraccting" > > Will Thanks for catching that. Cheers, Longman