netdev - Re: [PATCH net-next v5 0/4] Add support to do threaded napi busy poll

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250430133734.0e78a746@pumpkin>
Date: Wed, 30 Apr 2025 13:37:34 +0100
From: David Laight <david.laight.linux@...il.com>
To: Martin Karsten <mkarsten@...terloo.ca>
Cc: Willem de Bruijn <willemdebruijn.kernel@...il.com>, Joe Damato
 <jdamato@...tly.com>, Samiullah Khawaja <skhawaja@...gle.com>, Jakub
 Kicinski <kuba@...nel.org>, "David S . Miller" <davem@...emloft.net>, Eric
 Dumazet <edumazet@...gle.com>, Paolo Abeni <pabeni@...hat.com>,
 almasrymina@...gle.com, willemb@...gle.com, netdev@...r.kernel.org
Subject: Re: [PATCH net-next v5 0/4] Add support to do threaded napi busy
 poll

On Mon, 28 Apr 2025 14:05:17 -0400
Martin Karsten <mkarsten@...terloo.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