From: Andi Kleen <ak@linux.intel.com>
To: Alex Kogan <alex.kogan@oracle.com>
Cc: linux@armlinux.org.uk, Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
will.deacon@arm.com, arnd@arndb.de, longman@redhat.com,
linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, tglx@linutronix.de, bp@alien8.de,
hpa@zytor.com, x86@kernel.org, guohanjun@huawei.com,
jglauber@marvell.com, steven.sistare@oracle.com,
daniel.m.jordan@oracle.com, dave.dice@oracle.com
Subject: Re: [External] : Re: [PATCH v14 4/6] locking/qspinlock: Introduce starvation avoidance into CNA
Date: Tue, 13 Apr 2021 14:22:03 -0700 [thread overview]
Message-ID: <20210413212203.GT3762101@tassilo.jf.intel.com> (raw)
In-Reply-To: <CA1141EF-76A8-47A9-97B9-3CB2FC246B1A@oracle.com>
> > ms granularity seems very coarse grained for this. Surely
> > at some point of spinning you can afford a ktime_get? But ok.
> We are reading time when we are at the head of the (main) queue, but
> don’t have the lock yet. Not sure about the latency of ktime_get(), but
> anything reasonably fast but not necessarily precise should work.
Actually cpu_clock / sched_clock (see my other email). These should
be fast without corner cases and also monotonic.
>
> > Could you turn that into a moduleparm which can be changed at runtime?
> > Would be strange to have to reboot just to play with this parameter
> Yes, good suggestion, thanks.
>
> > This would also make the code a lot shorter I guess.
> So you don’t think we need the command-line parameter, just the module_param?
module_params can be changed at the command line too, so yes.
-Andi
WARNING: multiple messages have this Message-ID (diff)
From: Andi Kleen <ak@linux.intel.com>
To: Alex Kogan <alex.kogan@oracle.com>
Cc: linux@armlinux.org.uk, Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
will.deacon@arm.com, arnd@arndb.de, longman@redhat.com,
linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, tglx@linutronix.de, bp@alien8.de,
hpa@zytor.com, x86@kernel.org, guohanjun@huawei.com,
jglauber@marvell.com, steven.sistare@oracle.com,
daniel.m.jordan@oracle.com, dave.dice@oracle.com
Subject: Re: [External] : Re: [PATCH v14 4/6] locking/qspinlock: Introduce starvation avoidance into CNA
Date: Tue, 13 Apr 2021 14:22:03 -0700 [thread overview]
Message-ID: <20210413212203.GT3762101@tassilo.jf.intel.com> (raw)
In-Reply-To: <CA1141EF-76A8-47A9-97B9-3CB2FC246B1A@oracle.com>
> > ms granularity seems very coarse grained for this. Surely
> > at some point of spinning you can afford a ktime_get? But ok.
> We are reading time when we are at the head of the (main) queue, but
> don’t have the lock yet. Not sure about the latency of ktime_get(), but
> anything reasonably fast but not necessarily precise should work.
Actually cpu_clock / sched_clock (see my other email). These should
be fast without corner cases and also monotonic.
>
> > Could you turn that into a moduleparm which can be changed at runtime?
> > Would be strange to have to reboot just to play with this parameter
> Yes, good suggestion, thanks.
>
> > This would also make the code a lot shorter I guess.
> So you don’t think we need the command-line parameter, just the module_param?
module_params can be changed at the command line too, so yes.
-Andi
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next prev parent reply other threads:[~2021-04-13 21:22 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-01 15:31 [PATCH v14 0/6] Add NUMA-awareness to qspinlock Alex Kogan
2021-04-01 15:31 ` Alex Kogan
2021-04-01 15:31 ` [PATCH v14 1/6] locking/qspinlock: Rename mcs lock/unlock macros and make them more generic Alex Kogan
2021-04-01 15:31 ` Alex Kogan
2021-04-01 15:31 ` [PATCH v14 2/6] locking/qspinlock: Refactor the qspinlock slow path Alex Kogan
2021-04-01 15:31 ` Alex Kogan
2021-04-01 15:31 ` [PATCH v14 3/6] locking/qspinlock: Introduce CNA into the slow path of qspinlock Alex Kogan
2021-04-01 15:31 ` Alex Kogan
2021-04-13 11:30 ` Peter Zijlstra
2021-04-13 11:30 ` Peter Zijlstra
2021-04-14 2:29 ` [External] : " Alex Kogan
2021-04-14 2:29 ` Alex Kogan
2021-04-01 15:31 ` [PATCH v14 4/6] locking/qspinlock: Introduce starvation avoidance into CNA Alex Kogan
2021-04-01 15:31 ` Alex Kogan
2021-04-13 6:03 ` Andi Kleen
2021-04-13 6:03 ` Andi Kleen
2021-04-13 6:12 ` Andi Kleen
2021-04-13 6:12 ` Andi Kleen
2021-04-13 21:01 ` [External] : " Alex Kogan
2021-04-13 21:01 ` Alex Kogan
2021-04-13 21:22 ` Andi Kleen [this message]
2021-04-13 21:22 ` Andi Kleen
2021-04-14 2:30 ` Alex Kogan
2021-04-14 2:30 ` Alex Kogan
2021-04-14 16:41 ` Waiman Long
2021-04-14 16:41 ` Waiman Long
2021-04-14 17:26 ` Andi Kleen
2021-04-14 17:26 ` Andi Kleen
2021-04-14 17:31 ` Waiman Long
2021-04-14 17:31 ` Waiman Long
2021-04-13 12:03 ` Peter Zijlstra
2021-04-13 12:03 ` Peter Zijlstra
2021-04-16 2:52 ` [External] : " Alex Kogan
2021-04-16 2:52 ` Alex Kogan
2021-04-01 15:31 ` [PATCH v14 5/6] locking/qspinlock: Avoid moving certain threads between waiting queues in CNA Alex Kogan
2021-04-01 15:31 ` Alex Kogan
2021-04-01 15:31 ` [PATCH v14 6/6] locking/qspinlock: Introduce the shuffle reduction optimization into CNA Alex Kogan
2021-04-01 15:31 ` Alex Kogan
2021-04-14 7:47 ` Andreas Herrmann
2021-04-14 7:47 ` Andreas Herrmann
2021-04-14 18:18 ` [External] : " Alex Kogan
2021-04-14 18:18 ` Alex Kogan
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