All of lore.kernel.org
 help / color / mirror / Atom feed
From: "Dan Williams" <dan.j.williams@intel.com>
To: Liang Yang <multisyncfe991@hotmail.com>
Cc: linux-raid@vger.kernel.org
Subject: Re: What is the exacting meaning of Striped_Cache_Size?
Date: Sun, 21 Jan 2007 23:06:37 -0700	[thread overview]
Message-ID: <e9c3a7c20701212206p2316e02he13eebe8efc3889e@mail.gmail.com> (raw)
In-Reply-To: <BAY125-DAV159818650D5FE72FE853E393AE0@phx.gbl>

On 1/21/07, Liang Yang <multisyncfe991@hotmail.com> wrote:
> Hello,
>
> I have tried to increase the Striped_Cache_Size from 256 (default for my
> MD-RAID5 array) to 8192, it does improve the MD-RAID5 Write performance
> which varies with the size of I/O packet.
>
> However, I'm still not very clean the meaning and the potential performance
> impact of this Striped_Cache_Size? Is the unit for this parameter Byte or
> KiloByte?
>
> Could anyone here explain with a little bit more details?
>
stripe_cache_size is the number of stripes in the cache.  Each stripe
(strip) is composed one PAGE_SIZE block per disk.  If your page size
is 4k and you have 4 disks in your array then a stripe_cache_size of
256 is 4k * 4 * 256 = 4MB.

Increasing this number increases the chances that a write to the array
will not generate reads to satisfy the parity calculation.

> Thanks,
>
> Liang
>
Regards,

Dan

  reply	other threads:[~2007-01-22  6:06 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-01-20 12:23 Kernel 2.6.19.2 New RAID 5 Bug (oops when writing Samba -> RAID5) Justin Piszcz
2007-01-20 12:46 ` Justin Piszcz
2007-01-22  5:38   ` What is the exacting meaning of Striped_Cache_Size? Liang Yang
2007-01-22  5:38     ` Liang Yang
2007-01-22  6:06       ` Dan Williams [this message]
2007-01-22  6:22         ` Liang Yang
2007-01-22  6:22           ` Liang Yang
2007-01-22 16:36             ` Dan Williams
2007-01-22 21:01 ` Kernel 2.6.19.2 New RAID 5 Bug (oops when writing Samba -> RAID5) Chuck Ebbert
2007-01-22 21:59   ` Neil Brown
2007-01-23  1:44     ` Dan Williams
2007-01-23  2:06       ` Neil Brown
2007-01-23 10:56     ` Justin Piszcz
2007-01-23 11:08       ` Michael Tokarev
2007-01-23 11:59         ` Justin Piszcz
2007-01-23 12:48           ` Michael Tokarev
2007-01-23 13:46             ` Justin Piszcz
2007-01-23 17:05           ` Bill Davidsen
2007-01-24 23:37   ` Justin Piszcz
2007-01-26  9:25     ` Andrew Morton
2007-01-26  9:37       ` Justin Piszcz
2007-01-26 12:31       ` Justin Piszcz

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=e9c3a7c20701212206p2316e02he13eebe8efc3889e@mail.gmail.com \
    --to=dan.j.williams@intel.com \
    --cc=linux-raid@vger.kernel.org \
    --cc=multisyncfe991@hotmail.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.