From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Anton Blanchard <anton@samba.org>
Cc: linuxppc-dev@ozlabs.org, David Miller <davem@davemloft.net>
Subject: Re: [PATCH] Enable hashdist by default on 64bit NUMA
Date: Tue, 03 Mar 2009 16:27:15 +1100 [thread overview]
Message-ID: <1236058035.20465.19.camel@pasglop> (raw)
In-Reply-To: <20090226112431.GA25330@kryten>
On Thu, 2009-02-26 at 22:24 +1100, Anton Blanchard wrote:
> Hi David,
>
> > Hmmm... my bad, I think you need to keep the CONFIG_NUMA
> > there too as there is a TLB usage penalty for non-NUMA
> > systems if you only use CONFIG_64BIT there.
>
> Sorry that was my screwup, here's a fixed version.
Sounds good, how do we proceed for merging that ? Andrew ? Should it hop
by linux-mm ?
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
> Anton
>
> --
>
> On PowerPC we allocate large boot time hashes on node 0. This leads to
> an imbalance in the free memory, for example on a 64GB box (4 x 16GB
> nodes):
>
> Free memory:
> Node 0: 97.03%
> Node 1: 98.54%
> Node 2: 98.42%
> Node 3: 98.53%
>
> If we switch to using vmalloc (like ia64 and x86-64) things are more
> balanced:
>
> Free memory:
> Node 0: 97.53%
> Node 1: 98.35%
> Node 2: 98.33%
> Node 3: 98.33%
>
> For many HPC applications we are limited by the free available memory on
> the smallest node, so even though the same amount of memory is used the
> better balancing helps.
>
> Since all 64bit NUMA capable architectures should have sufficient
> vmalloc space, it makes sense to enable it via CONFIG_64BIT.
>
> Signed-off-by: Anton Blanchard <anton@samba.org>
> ---
>
> diff --git a/include/linux/bootmem.h b/include/linux/bootmem.h
> index 95837bf..0c4d4b7 100644
> --- a/include/linux/bootmem.h
> +++ b/include/linux/bootmem.h
> @@ -144,10 +144,10 @@ extern void *alloc_large_system_hash(const char *tablename,
>
> #define HASH_EARLY 0x00000001 /* Allocating during early boot? */
>
> -/* Only NUMA needs hash distribution.
> - * IA64 and x86_64 have sufficient vmalloc space.
> +/* Only NUMA needs hash distribution. 64bit NUMA architectures have
> + * sufficient vmalloc space.
> */
> -#if defined(CONFIG_NUMA) && (defined(CONFIG_IA64) || defined(CONFIG_X86_64))
> +#if defined(CONFIG_NUMA) && defined(CONFIG_64BIT)
> #define HASHDIST_DEFAULT 1
> #else
> #define HASHDIST_DEFAULT 0
> _______________________________________________
> Linuxppc-dev mailing list
> Linuxppc-dev@ozlabs.org
> https://ozlabs.org/mailman/listinfo/linuxppc-dev
prev parent reply other threads:[~2009-03-03 5:27 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-02-18 5:11 [PATCH] Enable hashdist by default on PowerPC Anton Blanchard
2009-02-18 5:41 ` Benjamin Herrenschmidt
2009-02-18 6:20 ` Anton Blanchard
2009-02-18 9:19 ` David Miller
2009-02-20 5:19 ` Anton Blanchard
2009-02-20 8:03 ` David Miller
2009-02-26 11:24 ` [PATCH] Enable hashdist by default on 64bit NUMA Anton Blanchard
2009-02-26 11:34 ` David Miller
2009-03-03 5:27 ` Benjamin Herrenschmidt [this message]
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=1236058035.20465.19.camel@pasglop \
--to=benh@kernel.crashing.org \
--cc=anton@samba.org \
--cc=davem@davemloft.net \
--cc=linuxppc-dev@ozlabs.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).