linux-kernel - Re: [Bug #11342] Linux 2.6.27-rc3: kernel BUG at mm/vmalloc.c

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: <48B5666E.2020509@sgi.com>
Date:	Wed, 27 Aug 2008 07:36:30 -0700
From:	Mike Travis <travis@....com>
To:	David Miller <davem@...emloft.net>
CC:	nickpiggin@...oo.com.au, davej@...hat.com,
	torvalds@...ux-foundation.org, Alan.Brunelle@...com, mingo@...e.hu,
	tglx@...utronix.de, rjw@...k.pl, linux-kernel@...r.kernel.org,
	kernel-testers@...r.kernel.org, akpm@...ux-foundation.org,
	arjan@...ux.intel.com, rusty@...tcorp.com.au,
	suresh.b.siddha@...el.com, tony.luck@...el.com, steiner@....com,
	cl@...ux-foundation.org
Subject: Re: [Bug #11342] Linux 2.6.27-rc3: kernel BUG at mm/vmalloc.c - bisected

David Miller wrote:
> From: Nick Piggin <nickpiggin@...oo.com.au>
> Date: Wed, 27 Aug 2008 16:54:32 +1000
> 
>> 5% is a pretty nasty performance hit... what sort of benchmarks are we
>> talking about here?
>>
>> I just made some pretty crazy changes to the VM to get "only" around 5
>> or so % performance improvement in some workloads.
>>
>> What places are making heavy use of cpumasks that causes such a slowdown?
>> Hopefully callers can mostly be improved so they don't need to use cpumasks
>> for common cases.
> 
> It's almost certainly from the cross-call dispatch call chain.
> 
> As just one example, just to do a TLB flush mm->cpu_vm_mask probably
> gets passed around as an aggregate two or three times on the way down
> to the APIC programming code on x86.  That's two or three 512 byte
> copies on the stack :)
> 
> Look at the sparc64 SMP code for how I solved the problem there.

I will, thanks!

Mike
--
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/