linux-kernel - Re: Ubuntu 32-bit, 32-bit PAE, 64-bit Kernel Benchmarks

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:	Thu, 31 Dec 2009 10:21:54 +0200
From:	Boaz Harrosh <bharrosh@...asas.com>
To:	Bill Davidsen <davidsen@....com>
CC:	Linux Kernel mailing List <linux-kernel@...r.kernel.org>
Subject: Re: Ubuntu 32-bit, 32-bit PAE, 64-bit Kernel Benchmarks

On 12/31/2009 04:49 AM, Bill Davidsen wrote:
> Yuhong Bao wrote:
>> Given that Linus was once talking about the performance penalties of PAE and HIGHMEM64G, perhaps you'd find these benchmarks done by Phoronix of interest:
>> http://www.phoronix.com/scan.php?page=article&item=ubuntu_32_pae
>>
> I find these tests mirror my own experience with PAE, the benefit of having the 
> nx hardware enabled justifies the few percent drop in performance I was able to 
> find.
> 
> I find the huge gain in web service hard to believe without a hint why a 64 bit 
> CPU would be 15x faster. The disk, memory, and network wouldn't be faster, and 
> the CPU intensive tests weren't significantly faster, so unless the systems were 
> tuned differently where's the gain? Same feeling about the TP test, an order of 
> magnitude faster on a test running the same application on the same hardware is 
> hard to buy without an explanation.
> 

Why? simple, Memory. This system must have lots of memory (see the HIGHMEM64G) so
lots of IO must be bouncing on a 32bit system, where in 64bit it is copy-less.

Just my guess, but I'm not surprised.

> The only obvious source I can think of is running the test load at 100Mbit on
> one test and Gbit on another, because I saw an early network driver do just that
> in negotiations with a switch.
> 

Boaz
--
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/