Prev: [PATCH tip/core/rcu 0/2] rcu: fixes for RCU lockdep
Next: [PATCH] ftrace: add tracing_thresh support to function_graph tracer (v3)
From: Rik van Riel on 25 Feb 2010 17:50
On 02/23/2010 10:10 PM, Wu Fengguang wrote:
> Collect readahead stats when CONFIG_READAHEAD_STATS=y.
>
> This is enabled by default because the added overheads are trivial:
> two readahead_stats() calls per readahead.
>
> Example output:
> (taken from a fresh booted NFS-ROOT box with rsize=16k)
>
> $ cat /debug/readahead/stats
> pattern readahead eof_hit cache_hit io sync_io mmap_io size async_size io_size
> initial 524 216 26 498 498 18 7 4 4
> subsequent 181 80 1 130 13 60 25 25 24
> context 94 28 3 85 64 8 7 2 5
> thrash 0 0 0 0 0 0 0 0 0
> around 162 121 33 162 162 162 60 0 21
> fadvise 0 0 0 0 0 0 0 0 0
> random 137 0 0 137 137 0 1 0 1
> all 1098 445 63 1012 874 0 17 6 9
>
> The two most important columns are
> - io number of readahead IO
> - io_size average readahead IO size
>
> CC: Ingo Molnar<mingo(a)elte.hu>
> CC: Jens Axboe<jens.axboe(a)oracle.com>
> CC: Peter Zijlstra<a.p.zijlstra(a)chello.nl>
> Signed-off-by: Wu Fengguang<fengguang.wu(a)intel.com>

Acked-by: Rik van Riel <riel(a)redhat.com>
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo(a)vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
 | 
Pages: 1
Prev: [PATCH tip/core/rcu 0/2] rcu: fixes for RCU lockdep
Next: [PATCH] ftrace: add tracing_thresh support to function_graph tracer (v3)