Messages in this thread Patch in this message | | | Date | Wed, 7 Dec 2011 17:18:20 +0800 | From | Wu Fengguang <> | Subject | Re: [PATCH 7/9] readahead: add vfs/readahead tracing event |
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On Tue, Dec 06, 2011 at 11:30:25PM +0800, Christoph Hellwig wrote: > > + TP_printk("readahead-%s(dev=%d:%d, ino=%lu, " > > please don't duplicate the tracepoint name in the output string. > Also don't use braces, as it jsut complicates parsing.
OK. Changed to this format:
TP_printk("pattern=%s bdi=%s ino=%lu " "req=%lu+%lu ra=%lu+%d-%d async=%d actual=%d",
> > + "req=%lu+%lu, ra=%lu+%d-%d, async=%d) = %d", > > + ra_pattern_names[__entry->pattern], > > Instead of doing a manual array lookup please use __print_symbolic so > that users of the binary interface (like trace-cmd) also get the > right output.
The patch actually started with
+#define show_pattern_name(val) \ + __print_symbolic(val, \ + { 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" })
It's then converted to the current form so as to avoid duplicating the num<>string mapping in two places.
The recently added writeback reason shares the same problem:
TP_printk("bdi %s: sb_dev %d:%d nr_pages=%ld sync_mode=%d " "kupdate=%d range_cyclic=%d background=%d reason=%s", ... wb_reason_name[__entry->reason] )
Fortunately that's newly introduced in 3.2-rc1, so it's still the good time to fix the writeback traces.
However the problem is, are we going to keep adding duplicate mappings like this in future?
> > --- linux-next.orig/mm/readahead.c 2011-11-29 20:58:53.000000000 +0800 > > +++ linux-next/mm/readahead.c 2011-11-29 20:59:20.000000000 +0800 > > @@ -29,6 +29,9 @@ static const char * const ra_pattern_nam > > [RA_PATTERN_ALL] = "all", > > }; > > > > +#define CREATE_TRACE_POINTS > > +#include <trace/events/vfs.h> > > Maybe we should create a new fs/trace.c just for this instead of stickin > it into the first file that created a tracepoint in the "vfs" namespace.
Yeah, it looks better to move it to a more general place.
Thanks, Fengguang
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