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From: Thomas Gleixner <tglx@linutronix.de>
To: Eric Dumazet <edumazet@google.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>,
	"Paul E . McKenney" <paulmck@kernel.org>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	"Rafael J . Wysocki" <rafael.j.wysocki@intel.com>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	"H. Peter Anvin" <hpa@zytor.com>,
	the arch/x86 maintainers <x86@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH] x86/cpu: use smp_call_function_many() in arch_freq_prepare_all()
Date: Wed, 30 Mar 2022 20:10:08 +0200	[thread overview]
Message-ID: <878rsrnwfz.ffs@tglx> (raw)
In-Reply-To: <CANn89iKnyG=3MbKzYKsE92p8Qu0QHie_UmQUxJx9YmHGUhKrQA@mail.gmail.com>

On Wed, Mar 30 2022 at 10:05, Eric Dumazet wrote:
> On Wed, Mar 30, 2022 at 10:02 AM Thomas Gleixner <tglx@linutronix.de> wrote:
>> On Wed, Mar 30 2022 at 09:51, Eric Dumazet wrote:
>> > On Wed, Mar 30, 2022 at 8:58 AM Thomas Gleixner <tglx@linutronix.de> wrote:
>> >> which I hate with a passion because that allows *unpriviledged* user
>> >> space to inject systemwide IPIs every 10ms just to read these counters
>> >> which are providing not more than some estimate and are of no value for
>> >> the only sane use case of /proc/cpuinfo, i.e. #1 above.
>> >
>> > You do realize that before my patch, this is already happening ?
>> >
>> > My "optimization" simply replace an open loop of individual IPI with
>> > use of the broadcast IPI capability.
>> >
>> > Are you saying we should remove IPI broadcast and use loops
>> > of IPI, one cpu at a time ?
>>
>> I rather have no IPIs at all...
>
> Can you send an actual patch, with a changelog then ?

I can polish up the patch I sent, split it up and add changelogs. Sure.

Thanks,

        tglx

      parent reply	other threads:[~2022-03-30 18:10 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-03-11  1:17 [PATCH] x86/cpu: use smp_call_function_many() in arch_freq_prepare_all() Eric Dumazet
2022-03-11 16:31 ` Paul E. McKenney
2022-03-11 16:35 ` Rafael J. Wysocki
2022-03-23 16:05   ` Eric Dumazet
2022-03-30 15:58 ` Thomas Gleixner
2022-03-30 16:51   ` Eric Dumazet
2022-03-30 17:02     ` Thomas Gleixner
2022-03-30 17:05       ` Eric Dumazet
2022-03-30 17:16         ` Eric Dumazet
2022-03-30 18:10         ` Thomas Gleixner [this message]

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