linux-kernel - Re: IRQ handling difference between i386 and x86

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]

Date:	Sun, 1 Jul 2007 00:53:01 +0200 (CEST)
From:	Krzysztof Oledzki <olel@....pl>
To:	Arjan van de Ven <arjan@...radead.org>
cc:	linux-kernel@...r.kernel.org
Subject: Re: IRQ handling difference between i386 and x86_64



On Sat, 30 Jun 2007, Arjan van de Ven wrote:

> On Sat, 2007-06-30 at 16:55 +0200, Krzysztof Oledzki wrote:
>> Hello,
>>
>> It seems that IRQ handling is somehow different between i386 and x86_64.
>>
>> In my Dell PowerEdge 1950 is it possible to enable interrupts spreading
>> over all CPUs. This a single CPU, four CORE system (Quad-Core E5335 Xeon)
>> so I think that interrupts migration may be useful. Unfortunately, it
>> works only with 32-bit kernel. Booting it with x86_64 leads to situation,
>> when all interrupts goes only to the first cpu matching a smp_affinity
>> mask.
>
> arguably that is the most efficient behavior... round robin of
> interrupts is the worst possible case in terms of performance

Even on dual/quadro core CPUs with shared cache? So why it is possible to 
enable such behaviuor in BIOS, which works only on i386 BTW. :(

> are you using irqbalance ? (www.irqbalance.org)

Yes, I'm aware about this useful tool, but in some situations (routing 
for example) it cannot help much as it keeps three cpus idle. :(

Best regards,

 				Krzysztof Olędzki