From: Stan Hoeppner <stan@hardwarefreak.com>
To: Jason Newton <nevion@gmail.com>
Cc: xfs@oss.sgi.com
Subject: Re: realtime section bugs still around
Date: Tue, 31 Jul 2012 22:55:51 -0500 [thread overview]
Message-ID: <5018A8C7.8050406@hardwarefreak.com> (raw)
In-Reply-To: <CAGou9MhneejOuhX4c8G06c3Zh7dxF-OtZ+=mT-7fho_u1Q3zWw@mail.gmail.com>
On 7/31/2012 6:55 PM, Jason Newton wrote:
> On Tue, Jul 31, 2012 at 4:46 PM, Stan Hoeppner <stan@hardwarefreak.com>wrote:
>
>> On 7/31/2012 6:01 PM, Jason Newton wrote:
>>
>>> I'm still interested in finding out why streaming a few hundred MB to
>> disk
>>> has so much over head in comparison to the calculations I do in
>> userspace,
>>
>> 1. md eats a lot of cycles at high data rates
>>
>
> md with intel's raid0? I stopped using linux/softraid, but I've read
> intel's is a mix between hardware and software raid...
Intel Matrix RAID is fakeraid. Designed for consumer workloads. You're
shoving a decidedly non consumer, high b/w IO stream through it. Don't
expect much. In fact I'm surprised you're using consumer grade gear for
this application. You are designing this software/system for a
commercial use case, correct? If so I'd get some better hardware.
CPU overhead for fakeraid will be similar to md/RAID, depending on the
vendor and implementation. In some cases it may be much higher than md.
> 2. ATA overhead
>> 3. IRQ/MSI overhead
>> 4. Etc.
>>
>> All these small bits add up to more than negligible CPU overhead at high
>> data rates.
>>
>
> Regarding the others, how would I go about measuring their overhead...
To what end?
--
Stan
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next prev parent reply other threads:[~2012-08-01 3:55 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-27 8:14 realtime section bugs still around Jason Newton
2012-07-27 9:56 ` Stan Hoeppner
2012-07-30 3:03 ` Dave Chinner
[not found] ` <CAGou9MheeBWxajd65szNfDB2L+VVoZ7SypEdUKj7np3L0H8fHA@mail.gmail.com>
2012-07-31 23:01 ` Jason Newton
2012-07-31 23:46 ` Stan Hoeppner
[not found] ` <CAGou9MhneejOuhX4c8G06c3Zh7dxF-OtZ+=mT-7fho_u1Q3zWw@mail.gmail.com>
2012-08-01 3:55 ` Stan Hoeppner [this message]
2012-08-01 5:55 ` Jason Newton
2012-08-02 0:39 ` Stan Hoeppner
2012-08-02 2:38 ` Jason Newton
2012-08-02 10:39 ` Stan Hoeppner
2012-08-03 11:28 ` Stan Hoeppner
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