From: Jason Gunthorpe <jgunthorpe-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
To: David Dillow <dillowda-1Heg1YXhbW8@public.gmane.org>
Cc: Or Gerlitz <ogerlitz-smomgflXvOZWk0Htik3J/w@public.gmane.org>,
linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Roland Dreier <rdreier-FYB4Gu1CFyUAvxtiuMwx3w@public.gmane.org>,
Eli Cohen <eli-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb@public.gmane.org>
Subject: Re: IB: increase DMA max_segment_size on Mellanox hardware
Date: Tue, 18 Jan 2011 11:01:29 -0700 [thread overview]
Message-ID: <20110118180129.GH995@obsidianresearch.com> (raw)
In-Reply-To: <1295353524.3051.121.camel-1q1vX8mYZiGLUyTwlgNVppKKF0rrzTr+@public.gmane.org>
On Tue, Jan 18, 2011 at 07:25:24AM -0500, David Dillow wrote:
> > Also when working with direct I/O from user space and/or under file-system,
> > did you really see many BIOs that can be merged? I was under the impression,
> > that (specifically after some time the system is active) for the most case,
> > I get totally scattered SGs, whose pages can't be coalesced at all.
>
> I would expect that to be a common case, but there are systems out there
> that this is not an issue. They typically allocate buffers early on when
> they can be contiguous, and just keep reusing those.
It has become really easy to use hugetlb now, you can just mmap
anonymous memory with MAP_HUGETLB and you get 2M pages. If an app is
using O_DIRECT it seem worth making an attempt to use huge pages..
IIRC databases are already doing this.
Jason
--
To unsubscribe from this list: send the line "unsubscribe linux-rdma" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
next prev parent reply other threads:[~2011-01-18 18:01 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-01-17 2:09 IB: increase DMA max_segment_size on Mellanox hardware David Dillow
[not found] ` <1295230184.2574.26.camel-1q1vX8mYZiGLUyTwlgNVppKKF0rrzTr+@public.gmane.org>
2011-01-17 11:16 ` Or Gerlitz
[not found] ` <4D342510.80701-smomgflXvOZWk0Htik3J/w@public.gmane.org>
2011-01-18 2:46 ` David Dillow
[not found] ` <1295318783.3051.81.camel-1q1vX8mYZiGLUyTwlgNVppKKF0rrzTr+@public.gmane.org>
2011-01-18 5:22 ` Jason Gunthorpe
2011-01-18 7:16 ` Or Gerlitz
[not found] ` <4D353E5E.2020500-smomgflXvOZWk0Htik3J/w@public.gmane.org>
2011-01-18 12:25 ` David Dillow
[not found] ` <1295353524.3051.121.camel-1q1vX8mYZiGLUyTwlgNVppKKF0rrzTr+@public.gmane.org>
2011-01-18 18:01 ` Jason Gunthorpe [this message]
2011-01-20 10:14 ` Or Gerlitz
[not found] ` <4D380AF2.4010905-smomgflXvOZWk0Htik3J/w@public.gmane.org>
2011-01-20 12:15 ` David Dillow
[not found] ` <1295525737.22825.24.camel-1q1vX8mYZiGLUyTwlgNVppKKF0rrzTr+@public.gmane.org>
2011-01-24 15:18 ` Or Gerlitz
[not found] ` <4D3D9845.4050803-smomgflXvOZWk0Htik3J/w@public.gmane.org>
2011-01-24 19:36 ` David Dillow
[not found] ` <1295897819.29946.17.camel-FqX9LgGZnHWDB2HL1qBt2PIbXMQ5te18@public.gmane.org>
2011-02-17 1:06 ` David Dillow
[not found] ` <1297904810.8833.44.camel-FqX9LgGZnHWDB2HL1qBt2PIbXMQ5te18@public.gmane.org>
2011-03-16 19:17 ` Or Gerlitz
2011-01-20 10:18 ` Or Gerlitz
[not found] ` <4D380BDC.5080002-smomgflXvOZWk0Htik3J/w@public.gmane.org>
2011-01-20 12:25 ` David Dillow
2011-03-22 8:01 ` Or Gerlitz
[not found] ` <4D885748.6060600-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
2011-03-22 12:51 ` David Dillow
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=20110118180129.GH995@obsidianresearch.com \
--to=jgunthorpe-epgobjl8dl3ta4ec/59zmfatqe2ktcn/@public.gmane.org \
--cc=dillowda-1Heg1YXhbW8@public.gmane.org \
--cc=eli-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb@public.gmane.org \
--cc=linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org \
--cc=ogerlitz-smomgflXvOZWk0Htik3J/w@public.gmane.org \
--cc=rdreier-FYB4Gu1CFyUAvxtiuMwx3w@public.gmane.org \
/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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox