Home » Mailing list archives » linux-kernel » 2008 » March » 26

Re: [PATCH 0/2] NR_CPUS: increase maximum NR_CPUS to 4096

Previous thread: [PATCH 12/12] cpu/node mask: reduce stack usage using MASK_NONE, MASK_ALL by Mike Travis on Tuesday, March 25, 2008 - 9:38 pm. (1 message)

Next thread: [PATCH 2/2] x86: Modify Kconfig to allow up to 4096 cpus by Mike Travis on Tuesday, March 25, 2008 - 9:41 pm. (7 messages)
[view original message]
From: Mike Travis <travis@...>
To: Andrew Morton <akpm@...>
Cc: Ingo Molnar <mingo@...>, <linux-mm@...>, <linux-kernel@...>
Subject: [PATCH 0/2] NR_CPUS: increase maximum NR_CPUS to 4096
Date: Tuesday, March 25, 2008 - 9:41 pm

Increases the limit of NR_CPUS to 4096 and introduces a

boolean called "MAXSMP" which when set (e.g. "allyesconfig")

will set NR_CPUS = 4096 and NODES_SHIFT = 9 (512).


I've been running this config (4k NR_CPUS, 512 Max Nodes)

on an AMD box with 2 dual-cores and 4gb memory.  I've also

successfully booted it in a simulated 2cpus/1Gb environment.


Based on:

	git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git

	git://git.kernel.org/pub/scm/linux/kernel/git/x86/linux-2.6-x86.git


Signed-off-by: Mike Travis <travis@sgi.com>

---


Memory usage effects from upping NR_CPUS to 4096 and MAX_NUMANODES to 512.


255-akpm2: akpm2 config with NR_CPUS=255  / NUMA_NODE_SHIFT=6

4k-akpm2:  akpm2 config with NR_CPUS=4096 / NUMA_NODE_SHIFT=9


====== Data (-l 1000)

    1 - 255-akpm2

    2 - 4k-akpm2


      .1.       .2.    ..final..

  1114112  +3899392 5013504  +350%  irq_desc(.data.cacheline_aligned)

   313344  +4177920 4491264 +1333%  irq_cfg(.data.read_mostly)

    76800   +537600  614400  +700%  early_node_map(.init.data)

    32640   +491648  524288 +1506%  boot_pageset(.bss)

    32640   +491648  524288 +1506%  boot_cpu_pda(.data.cacheline_aligned)

    23040   +161280  184320  +700%  initkmem_list3(.init.data)

     5632    +39424   45056  +700%  node_devices(.bss)

     4096    +28672   32768  +700%  plat_node_bdata(.bss)

     2656    +34312   36968 +1291%  cache_cache(.data)

     2048    +14336   16384  +700%  rio_devs(.init.data)

     2048   +260096  262144 +12700%  node_to_cpumask_map(.data.read_mostly)

     2040    +30728   32768 +1506%  centrino_model(.bss)

     2040    +30728   32768 +1506%  centrino_cpu(.bss)

     2040    +30728   32768 +1506%  _cpu_pda(.data.read_mostly)

     1024     +1024    2048  +100%  pxm_to_node_map(.data)

     1024     +7168    8192  +700%  nodes_add(.bss)

     1024     +7168    8192  +700%  nodes(.init.data)

     1024     +7168    8192  +700%  hugepage_freelists(.bss)

     1020    +15364   16384 +1506%  x86_cpu_to_node_map_init(.data)...
[ message continues ]
[view original message]
From: Ingo Molnar <mingo@...>
To: Mike Travis <travis@...>
Cc: Andrew Morton <akpm@...>, <linux-mm@...>, <linux-kernel@...>
Subject: Re: [PATCH 0/2] NR_CPUS: increase maximum NR_CPUS to 4096
Date: Wednesday, March 26, 2008 - 2:19 am

cool!


this depends on the cpumask changes to work correctly (i.e. to boot at

all), right?


	Ingo

--
[view original message]
From: Mike Travis <travis@...>
To: Ingo Molnar <mingo@...>
Cc: Andrew Morton <akpm@...>, <linux-mm@...>, <linux-kernel@...>
Subject: Re: [PATCH 0/2] NR_CPUS: increase maximum NR_CPUS to 4096
Date: Wednesday, March 26, 2008 - 11:59 am

Yes, it overflows the stack quite quickly without the cpumask changes.

I didn't do any testing to see what's the minimal set of changes.


Thanks,

Mike

--
Previous thread: [PATCH 12/12] cpu/node mask: reduce stack usage using MASK_NONE, MASK_ALL by Mike Travis on Tuesday, March 25, 2008 - 9:38 pm. (1 message)

Next thread: [PATCH 2/2] x86: Modify Kconfig to allow up to 4096 cpus by Mike Travis on Tuesday, March 25, 2008 - 9:41 pm. (7 messages)