From: Christopher Lameter <cl@linux.com>
To: Barret Rhoden <brho@google.com>
Cc: Dennis Zhou <dennis@kernel.org>,
Eial Czerwacki <eial@scalemp.com>,
tj@kernel.org, linux-kernel@vger.kernel.org,
Shai Fultheim <shai@scalemp.com>, Oren Twaig <oren@scalemp.com>,
"Paul E. McKenney" <paulmck@linux.ibm.com>
Subject: Re: [PATCH] percpu/module resevation: change resevation size iff X86_VSMP is set
Date: Thu, 4 Apr 2019 20:53:28 +0000 [thread overview]
Message-ID: <01000169ea20bd44-f3d23988-e21e-4c0a-8e54-d8e54bbaa237-000000@email.amazonses.com> (raw)
In-Reply-To: <85726648-82f3-6b6b-a749-03c4159e78f3@google.com>
On Wed, 13 Mar 2019, Barret Rhoden wrote:
> > It is very expensive. VMSP exchanges 4K segments via RDMA between servers
> > to build a large address space and run a kernel in the large address
> > space. Using smaller segments can cause a lot of
> > "cacheline" bouncing (meaning transfers of 4K segments back and forth
> > between servers).
> >
>
> Given that these are large machines, would it be OK to statically reserve 64K
> on them for modules' percpu data?
Likely.
> The bug that led me to here was from someone running on a non-VSMP machine but
> had that config set. Perhaps we make it more clear in the Kconfig option to
> not set it on other machines. That might make it less likely anyone on a
> non-VSMP machine pays the 64K overhead.
Right.
> Are there any other alternatives? Not using static SRCU in any code that
> could be built as a module seems a little harsh.
Sorry this ended up in my spam folder somehow. Just fished it out.
next prev parent reply other threads:[~2019-04-04 20:53 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-21 11:47 [PATCH] percpu/module resevation: change resevation size iff X86_VSMP is set Eial Czerwacki
2019-01-30 10:33 ` Eial Czerwacki
2019-03-01 18:30 ` Barret Rhoden
2019-03-01 20:34 ` Dennis Zhou
2019-03-01 21:27 ` Barret Rhoden
2019-03-01 21:54 ` Christopher Lameter
2019-03-13 19:40 ` Barret Rhoden
2019-03-13 20:26 ` Tejun Heo
2019-03-13 21:22 ` Paul E. McKenney
2019-03-13 21:29 ` Tejun Heo
2019-03-13 23:11 ` Paul E. McKenney
2019-03-14 17:36 ` Tejun Heo
2019-03-14 22:19 ` Paul E. McKenney
2019-03-18 8:18 ` Eial Czerwacki
2019-03-18 14:27 ` Paul E. McKenney
2019-04-04 20:53 ` Christopher Lameter [this message]
2019-03-04 7:42 ` Eial Czerwacki
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=01000169ea20bd44-f3d23988-e21e-4c0a-8e54-d8e54bbaa237-000000@email.amazonses.com \
--to=cl@linux.com \
--cc=brho@google.com \
--cc=dennis@kernel.org \
--cc=eial@scalemp.com \
--cc=linux-kernel@vger.kernel.org \
--cc=oren@scalemp.com \
--cc=paulmck@linux.ibm.com \
--cc=shai@scalemp.com \
--cc=tj@kernel.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;
as well as URLs for NNTP newsgroup(s).