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| author | Mike Travis <travis@sgi.com> | 2011-05-24 17:13:12 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2011-05-25 08:39:45 -0700 |
| commit | 4b060420a596095869a6d7849caa798d23839cd1 (patch) | |
| tree | ebbbc25555d0358f73527f114f78691ac849ce3e /Documentation/filesystems/proc.txt | |
| parent | e50c1f609c63223adaa38f5a79b18759a00adf72 (diff) | |
| download | lwn-4b060420a596095869a6d7849caa798d23839cd1.tar.gz lwn-4b060420a596095869a6d7849caa798d23839cd1.zip | |
bitmap, irq: add smp_affinity_list interface to /proc/irq
Manually adjusting the smp_affinity for IRQ's becomes unwieldy when the
cpu count is large.
Setting smp affinity to cpus 256 to 263 would be:
echo 000000ff,00000000,00000000,00000000,00000000,00000000,00000000,00000000 > smp_affinity
instead of:
echo 256-263 > smp_affinity_list
Think about what it looks like for cpus around say, 4088 to 4095.
We already have many alternate "list" interfaces:
/sys/devices/system/cpu/cpuX/indexY/shared_cpu_list
/sys/devices/system/cpu/cpuX/topology/thread_siblings_list
/sys/devices/system/cpu/cpuX/topology/core_siblings_list
/sys/devices/system/node/nodeX/cpulist
/sys/devices/pci***/***/local_cpulist
Add a companion interface, smp_affinity_list to use cpu lists instead of
cpu maps. This conforms to other companion interfaces where both a map
and a list interface exists.
This required adding a bitmap_parselist_user() function in a manner
similar to the bitmap_parse_user() function.
[akpm@linux-foundation.org: make __bitmap_parselist() static]
Signed-off-by: Mike Travis <travis@sgi.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jack Steiner <steiner@sgi.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation/filesystems/proc.txt')
| -rw-r--r-- | Documentation/filesystems/proc.txt | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt index 60740e8ecb37..f48178024067 100644 --- a/Documentation/filesystems/proc.txt +++ b/Documentation/filesystems/proc.txt @@ -574,6 +574,12 @@ The contents of each smp_affinity file is the same by default: > cat /proc/irq/0/smp_affinity ffffffff +There is an alternate interface, smp_affinity_list which allows specifying +a cpu range instead of a bitmask: + + > cat /proc/irq/0/smp_affinity_list + 1024-1031 + The default_smp_affinity mask applies to all non-active IRQs, which are the IRQs which have not yet been allocated/activated, and hence which lack a /proc/irq/[0-9]* directory. @@ -583,12 +589,13 @@ reports itself as being attached. This hardware locality information does not include information about any possible driver locality preference. prof_cpu_mask specifies which CPUs are to be profiled by the system wide -profiler. Default value is ffffffff (all cpus). +profiler. Default value is ffffffff (all cpus if there are only 32 of them). The way IRQs are routed is handled by the IO-APIC, and it's Round Robin between all the CPUs which are allowed to handle it. As usual the kernel has more info than you and does a better job than you, so the defaults are the -best choice for almost everyone. +best choice for almost everyone. [Note this applies only to those IO-APIC's +that support "Round Robin" interrupt distribution.] There are three more important subdirectories in /proc: net, scsi, and sys. The general rule is that the contents, or even the existence of these |