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From: David Laight <david.laight.linux@gmail.com>
To: Martin Karsten <mkarsten@uwaterloo.ca>
Cc: Willem de Bruijn <willemdebruijn.kernel@gmail.com>,
	Joe Damato <jdamato@fastly.com>,
	Samiullah Khawaja <skhawaja@google.com>,
	Jakub Kicinski <kuba@kernel.org>,
	"David S . Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Paolo Abeni <pabeni@redhat.com>,
	almasrymina@google.com, willemb@google.com,
	netdev@vger.kernel.org
Subject: Re: [PATCH net-next v5 0/4] Add support to do threaded napi busy poll
Date: Wed, 30 Apr 2025 13:37:34 +0100	[thread overview]
Message-ID: <20250430133734.0e78a746@pumpkin> (raw)
In-Reply-To: <5fa8c9b8-527c-4392-9c9f-4e1e93ab5326@uwaterloo.ca>

On Mon, 28 Apr 2025 14:05:17 -0400
Martin Karsten <mkarsten@uwaterloo.ca> wrote:

...
> That's not the same. The existing busy-poll mechanism still needs an 
> application thread. This thing will just go off and spin, whether 
> there's an application or not.

I think this (and elsewhere) should be 'busy spin' not 'busy poll'.
That would make it much more obvious that it really is a cpu intensive
spin loop.

Note that on some cpu all the 'cores' run at the same speed.
So that putting one into a 'spin' will cause the frequency of all of
them to increase - thus speeding up a benchmark.

Rather the opposite of tests where a cpu busy thread (doing work)
gets bounced around physical cpu - so keeps being run on ones
running a low clock speed.

	David

  reply	other threads:[~2025-04-30 12:37 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-04-24 20:02 [PATCH net-next v5 0/4] Add support to do threaded napi busy poll Samiullah Khawaja
2025-04-24 20:02 ` [PATCH net-next v5 1/4] net: Create separate gro_flush helper function Samiullah Khawaja
2025-04-24 23:21   ` Joe Damato
2025-04-24 20:02 ` [PATCH net-next v5 2/4] net: define an enum for the napi threaded state Samiullah Khawaja
2025-04-24 23:40   ` Joe Damato
2025-04-26  1:36   ` Jakub Kicinski
2025-04-26  3:54     ` Samiullah Khawaja
2025-04-24 20:02 ` [PATCH net-next v5 3/4] Extend napi threaded polling to allow kthread based busy polling Samiullah Khawaja
2025-04-24 23:42   ` Joe Damato
2025-04-24 20:02 ` [PATCH net-next v5 4/4] selftests: Add napi threaded busy poll test in `busy_poller` Samiullah Khawaja
2025-04-28 13:50 ` [PATCH net-next v5 0/4] Add support to do threaded napi busy poll Martin Karsten
2025-04-28 16:52   ` Willem de Bruijn
2025-04-28 17:39     ` Joe Damato
2025-04-28 17:59       ` Willem de Bruijn
2025-04-28 18:05         ` Martin Karsten
2025-04-30 12:37           ` David Laight [this message]
2025-04-30 16:47             ` Samiullah Khawaja
2025-04-28 18:05     ` Martin Karsten
2025-04-28 18:20       ` Willem de Bruijn
2025-04-30 15:23   ` Martin Karsten
2025-04-30 16:58     ` Samiullah Khawaja
2025-04-30 19:57       ` Martin Karsten
2025-04-30 20:33         ` Samiullah Khawaja

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