linux-kernel - Re: [PATCH 3/3] x86/iommu: use __GFP

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: <20080929085647.GB2190@elte.hu>
Date:	Mon, 29 Sep 2008 10:56:47 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Joerg Roedel <joerg.roedel@....com>
Cc:	mingo@...hat.com, tglx@...utronix.de, hpa@...or.com,
	linux-kernel@...r.kernel.org, fujita.tomonori@....ntt.co.jp
Subject: Re: [PATCH 3/3] x86/iommu: use __GFP_ZERO instead of memset for
	GART


* Joerg Roedel <joerg.roedel@....com> wrote:

> On Sat, Sep 27, 2008 at 08:18:55PM +0200, Ingo Molnar wrote:
> > 
> > another thing:
> > 
> > How hard would it be to add an CONFIG_IOMMU_DEBUG option that forces as 
> > many DMA requests to go via the IOMMU as possible?
> > 
> > This slows things down of course so it's only for debugging - but it 
> > also makes sure that we utilize the IOMMU code to the maximum - which is 
> > not normally the case.
> > 
> > Would be nice to have it .config driven (default-disabled), so that 
> > -tip's randconfig testing can stumble upon it every now and then. I've 
> > got GART test-systems - this way we could find certain types of IOMMU 
> > breakages sooner.
> 
> For AMD IOMMU I disabled the round-robin allocator to stress-test the 
> code. This means that the address allocation bitmap is always 
> traversed from the first bit. In consequence the TLB flushing is 
> stressed a lot (both in hardware and software) because the same DMA 
> addresses are used again and again. For testing I hardcoded it into 
> the driver but I can also make it depend on CONFIG_IOMMU_DEBUG.

yes - could you please make a new option for it, 
CONFIG_IOMMU_DEBUG_FORCE=y or so - and cover all iommus that support it?

	Ingo
--
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/