linux-kernel - Re: [PATCH] msi: skip calling pci_find_capability from msi_set_mask

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: <20080520195609.GC6714@ghostprotocols.net>
Date:	Tue, 20 May 2008 16:56:09 -0300
From:	Arnaldo Carvalho de Melo <acme@...hat.com>
To:	Jesse Barnes <jbarnes@...tuousgeek.org>
Cc:	Hidetoshi Seto <seto.hidetoshi@...fujitsu.com>,
	Matthew Wilcox <matthew@....cx>, linux-kernel@...r.kernel.org,
	linux-pci@...r.kernel.org, linux-rt-users@...r.kernel.org
Subject: Re: [PATCH] msi: skip calling pci_find_capability from
	msi_set_mask_bits

Em Mon, May 19, 2008 at 01:11:45PM -0700, Jesse Barnes escreveu:
> On Sunday, May 18, 2008 9:48 pm Hidetoshi Seto wrote:
> > Jesse Barnes wrote:
> > > Since we know MSI is a problem, let's just go with fixing that for now. 
> > > If we find that other caps are also causing problems we can revisit
> > > caching all of them; the patch is simple enough.
> >
> > Humm...
> > I suppose it can be more simple. How about this patch?
> >
> > > everytime handle_edge_irq is called it needs to mask and unmask MSI, and
> > > that leads to a series of very expensive calls to pci_find_capability
> >
> > The position of MSI capability is already cached in the msi_desc when
> > we enter the msi_set_mask_bits().  Use it instead.
> >
> > Signed-off-by: Hidetoshi Seto <seto.hidetoshi@...fujitsu.com>
> 
> Yeah, this looks really nice.  It should also fix Arnaldo's latency problem, 
> and really looks like a bug fix for the MSI code more than anything.
> 
> Arnaldo, can you take a look & test and ack/nack?

Tested, works as expected, thanks.

Acked-by: Arnaldo Carvalho de Melo <acme@...hat.com>

- Arnaldo
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/