Example output: # echo 1 > /debug/tracing/events/readahead/enable # cp test-file /dev/null # cat /debug/tracing/trace # trimmed output readahead-initial(dev=0:15, ino=100177, req=0+2, ra=0+4-2, async=0) = 4 readahead-subsequent(dev=0:15, ino=100177, req=2+2, ra=4+8-8, async=1) = 8 readahead-subsequent(dev=0:15, ino=100177, req=4+2, ra=12+16-16, async=1) = 16 readahead-subsequent(dev=0:15, ino=100177, req=12+2, ra=28+32-32, async=1) = 32 readahead-subsequent(dev=0:15, ino=100177, req=28+2, ra=60+60-60, async=1) = 24 readahead-subsequent(dev=0:15, ino=100177, req=60+2, ra=120+60-60, async=1) = 0 CC: Ingo Molnar CC: Jens Axboe CC: Peter Zijlstra Signed-off-by: Wu Fengguang --- include/trace/events/readahead.h | 69 +++++++++++++++++++++++++++++ mm/readahead.c | 22 +++++++++ 2 files changed, 91 insertions(+) --- /dev/null 1970-01-01 00:00:00.000000000 +0000 +++ linux/include/trace/events/readahead.h 2010-02-07 11:46:42.000000000 +0800 @@ -0,0 +1,69 @@ +#undef TRACE_SYSTEM +#define TRACE_SYSTEM readahead + +#if !defined(_TRACE_READAHEAD_H) || defined(TRACE_HEADER_MULTI_READ) +#define _TRACE_READAHEAD_H + +#include + +extern const char * const ra_pattern_names[]; + +/* + * Tracepoint for guest mode entry. + */ +TRACE_EVENT(readahead, + TP_PROTO(struct address_space *mapping, + pgoff_t offset, + unsigned long req_size, + unsigned int ra_flags, + pgoff_t start, + unsigned int size, + unsigned int async_size, + unsigned int actual), + + TP_ARGS(mapping, offset, req_size, + ra_flags, start, size, async_size, actual), + + TP_STRUCT__entry( + __field( dev_t, dev ) + __field( ino_t, ino ) + __field( pgoff_t, offset ) + __field( unsigned long, req_size ) + __field( unsigned int, pattern ) + __field( pgoff_t, start ) + __field( unsigned int, size ) + __field( unsigned int, async_size ) + __field( unsigned int, actual ) + ), + + TP_fast_assign( + __entry->dev = mapping->host->i_sb->s_dev; + __entry->ino = mapping->host->i_ino; + __entry->pattern = ra_pattern(ra_flags); + __entry->offset = offset; + __entry->req_size = req_size; + __entry->start = start; + __entry->size = size; + __entry->async_size = async_size; + __entry->actual = actual; + ), + + TP_printk("readahead-%s(dev=%d:%d, ino=%lu, " + "req=%lu+%lu, ra=%lu+%d-%d, async=%d) = %d", + ra_pattern_names[__entry->pattern], + MAJOR(__entry->dev), + MINOR(__entry->dev), + __entry->ino, + __entry->offset, + __entry->req_size, + __entry->start, + __entry->size, + __entry->async_size, + __entry->start > __entry->offset, + __entry->actual) +); + +#endif /* _TRACE_READAHEAD_H */ + +/* This part must be outside protection */ +#include --- linux.orig/mm/readahead.c 2010-02-07 11:46:40.000000000 +0800 +++ linux/mm/readahead.c 2010-02-07 11:46:42.000000000 +0800 @@ -19,11 +19,25 @@ #include #include +#define CREATE_TRACE_POINTS +#include + /* * Set async size to 1/# of the thrashing threshold. */ #define READAHEAD_ASYNC_RATIO 8 +const char * const ra_pattern_names[] = { + [RA_PATTERN_INITIAL] = "initial", + [RA_PATTERN_SUBSEQUENT] = "subsequent", + [RA_PATTERN_CONTEXT] = "context", + [RA_PATTERN_THRASH] = "thrash", + [RA_PATTERN_MMAP_AROUND] = "around", + [RA_PATTERN_FADVISE] = "fadvise", + [RA_PATTERN_RANDOM] = "random", + [RA_PATTERN_ALL] = "all", +}; + /* * Initialise a struct file's readahead state. Assumes that the caller has * memset *ra to zero. @@ -274,6 +288,11 @@ int force_page_cache_readahead(struct ad offset += this_chunk; nr_to_read -= this_chunk; } + + trace_readahead(mapping, offset, nr_to_read, + RA_PATTERN_FADVISE << READAHEAD_PATTERN_SHIFT, + offset, nr_to_read, 0, ret); + return ret; } @@ -301,6 +320,9 @@ unsigned long ra_submit(struct file_ra_s actual = __do_page_cache_readahead(mapping, filp, ra->start, ra->size, ra->async_size); + trace_readahead(mapping, offset, req_size, ra->ra_flags, + ra->start, ra->size, ra->async_size, actual); + return actual; } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/