Pasi Kärkkäinen wrote:
On Fri, Jun 18, 2010 at 12:10:04PM +0300, guy keren wrote:
Pasi Kärkkäinen wrote:
On Mon, Jun 14, 2010 at 11:39:47PM +0400, Vladislav Bolkhovitin wrote:
Pasi Kärkkäinen, on 06/11/2010 11:26 AM wrote:
On Fri, Feb 05, 2010 at 02:10:32PM +0300, Vladislav Bolkhovitin wrote:
Pasi Kärkkäinen, on 01/28/2010 03:36 PM wrote:
Hello list,

Please check these news items:

"1,030,000 IOPS over a single 10 Gb Ethernet link"

"Specifically, Intel and Microsoft clocked 1,030,000 IOPS (with 512-byte blocks), and more than 2,250MBps with large block sizes (16KB to 256KB) using the Iometer benchmark"

So.. who wants to beat that using Linux + open-iscsi? :)
I personally, don't like such tests and don't trust them at all. They are pure marketing. The only goal of them is to create impression that X (Microsoft and Windows in this case) is a super-puper ahead of the world. I've seen on the Web a good article about usual tricks used by vendors to cheat benchmarks to get good marketing material, but, unfortunately, can't find link on it at the moment.

The problem is that you can't say from such tests if X will also "ahead of the world" on real life usages, because such tests always heavily optimized for particular used benchmarks and such optimizations almost always hurt real life cases. And you hardly find descriptions of those optimizations as well as a scientific description of the tests themself. The results published practically only in marketing documents.

Anyway, as far as I can see Linux supports all the used hardware as well as all advance performance modes of it, so if one repeats this test in the same setup, he/she should get not worse results.

For me personally it was funny to see how MS presents in the WinHEC presentation ( that they have 1.1GB/s from 4 connections. In the beginning of 2008 I saw a *single* dd pushing data on that rate over a *single* connection from Linux initiator to iSCSI-SCST target using regular Myricom hardware without any special acceleration. I didn't know how proud I must have been for Linux :).

It seems they've described the setup here:

And today they seem to have a demo which produces 1.3 million IOPS!

"1 Million IOPS? How about 1.25 Million!":
I'm glad for them. The only thing surprises me that none of the Linux vendors, including Intel itself, interested to repeat this test for Linux and fix possible found problems, if any. Ten years ago similar test about Linux TCP scalability limitations comparing with Windows caused massive reaction and great TCP improvements.

Yeah, I'd like to see this aswell.
I don't think I have enough extra hardware myself.. atm.

Does someone have enough boxes with 10 Gbit connections? :)

The way how to do the test is quite straightforward, starting from making for Linux similarly effective test tool as IOMeter on Windows [1]. Maybe, the lack of such tool scares the vendors away?

I'm wondering how big effort it would be to fix IOmeter for linux.. iirc there were some patches to fix the AIO stuff.
the AIO stuff inside IOMeter won't necessarily help, since the AIO implementation in linux kernels is not efficient enough*

* note: i'm only updated to kernel 2.6.18 - but i didn't here there was a strong effort to make this better in newer kernels. correct me if i'm wrong.

So what's the actual problem?

as far as i know - sometimes, AIO requests are handled in a synchronous manner - so it's not AIO all the way. maybe this has become better in later kernels - but i doubt that.


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