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Re: dd PATCH: add conv=direct
From: |
Anton Blanchard |
Subject: |
Re: dd PATCH: add conv=direct |
Date: |
Fri, 9 Apr 2004 10:37:37 +1000 |
User-agent: |
Mutt/1.5.5.1+cvs20040105i |
Hi,
> OK, I can see that one. But it seems like a pretty small benefit to me
> -- CPU utilization is already really low.
Maybe not to you but it does make a big difference on our 500 disk setup.
At the moment we use dd to do an initial sniff, then ext3 utils to do
O_DIRECT reads/writes. With O_DIRECT read/write in dd we could use it
instead. (We are basically interested in IO performance that a database
would see).
> Um, that sounds like a bad idea to me. It seems to me it's the kernel's
> responsibility to figure out "hey, looks like a streaming read - let's
> not blow out the buffer cache trying to hold 20GB on a 512M system." If
> you're saying that the kernel guys have given up and the established
> wisdom is now "you gotta use O_DIRECT if you don't want to throw
> everything else out due to streaming data", well... I'm disappointed.
When you start hitting memory bandwidth limits, O_DIRECT will help you.
Sure it wont be an issue for your dd copy scenario, but I wanted to point
out there are other valid uses for it.
Anton
- Re: dd PATCH: add conv=direct, (continued)
- Re: dd PATCH: add conv=direct, Paul Eggert, 2004/04/08
- Re: dd PATCH: add conv=direct, Jim Meyering, 2004/04/08
- Re: dd PATCH: add conv=direct, Paul Eggert, 2004/04/08
- Re: dd PATCH: add conv=direct, Paul Jarc, 2004/04/08
- Re: dd PATCH: add conv=direct, Jim Meyering, 2004/04/08
- Re: dd PATCH: add conv=direct, Philippe Troin, 2004/04/08
- dd patch to remove noctty, Paul Eggert, 2004/04/08
- Re: dd patch to remove noctty, Jim Meyering, 2004/04/08
- Message not available
- Re: dd PATCH: add conv=direct, Paul Eggert, 2004/04/19
- Re: dd PATCH: add conv=direct, James Antill, 2004/04/20
- Re: dd PATCH: add conv=direct,
Anton Blanchard <=
- Re: dd PATCH: add conv=direct, Wim Coekaerts, 2004/04/10
- Re: dd PATCH: add conv=direct, Jim Meyering, 2004/04/10
- Message not available
- Message not available
- Message not available
- coreutils patch to align buffers better, Paul Eggert, 2004/04/13
- Re: coreutils patch to align buffers better, Jim Meyering, 2004/04/15
- Message not available
- Message not available
- Message not available
- Re: dd PATCH: add conv=direct, Paul Eggert, 2004/04/13
- Re: dd PATCH: add conv=direct, Bryce, 2004/04/14
- Re: dd PATCH: add conv=direct, Paul Eggert, 2004/04/14
- Re: dd PATCH: add conv=direct, Jim Meyering, 2004/04/14
- Re: dd PATCH: add conv=direct, Bryce, 2004/04/15
- Re: dd PATCH: add conv=direct, Bryce, 2004/04/15