path: root/tools/perf/design.txt
diff options
authorPeter Zijlstra <>2009-09-21 16:08:49 +0200
committerIngo Molnar <>2009-10-06 14:21:50 +0200
commit906010b2134e14a2e377decbadd357b3d0ab9c6a (patch)
tree598b30d08f5ca8df1e00abc295b120fa1bd2c2e2 /tools/perf/design.txt
parente13dbd7d75d1ecc315c6e3071b3c4e8fba4f6bec (diff)
perf_event: Provide vmalloc() based mmap() backing
Some architectures such as Sparc, ARM and MIPS (basically everything with flush_dcache_page()) need to deal with dcache aliases by carefully placing pages in both kernel and user maps. These architectures typically have to use vmalloc_user() for this. However, on other architectures, vmalloc() is not needed and has the downsides of being more restricted and slower than regular allocations. Signed-off-by: Peter Zijlstra <> Acked-by: David Miller <> Cc: Andrew Morton <> Cc: Jens Axboe <> Cc: Paul Mackerras <> LKML-Reference: <1254830228.21044.272.camel@laptop> Signed-off-by: Ingo Molnar <>
Diffstat (limited to 'tools/perf/design.txt')
1 files changed, 3 insertions, 0 deletions
diff --git a/tools/perf/design.txt b/tools/perf/design.txt
index f1946d107b10..fdd42a824c98 100644
--- a/tools/perf/design.txt
+++ b/tools/perf/design.txt
@@ -455,3 +455,6 @@ will need at least this:
If your architecture does have hardware capabilities, you can override the
weak stub hw_perf_event_init() to register hardware counters.
+Architectures that have d-cache aliassing issues, such as Sparc and ARM,
+should select PERF_USE_VMALLOC in order to avoid these for perf mmap().