On Thu, 2006-12-21 at 15:19 +0100, Jens Axboe wrote:
> On Thu, Dec 21 2006, Seetharami Seelam wrote:
> > On 12/21/06, Jens Axboe <[EMAIL PROTECTED]> wrote:
> > >
> > >On Thu, Dec 21 2006, Ming Zhang wrote:
> > >> On Thu, 2006-12-21 at 08:42 +0100, Jens Axboe wrote:
> > >> > On Wed, Dec 20 2006, Ming Zhang wrote:
> > >> > > On Wed, 2006-12-20 at 14:09 -0600, Seetharami Seelam wrote:
> > >> > > >
> > >> > > > On 12/20/06, Ming Zhang <[EMAIL PROTECTED]> wrote:
> > >> > > >         On Wed, 2006-12-20 at 17:45 +0100, Jens Axboe wrote:
> > >> > > >         > On Wed, Dec 20 2006, Ming Zhang wrote:
> > >> > > >         > >
> > >> > > >         > > On Wed, 2006-12-20 at 14:02 +0100, Jens Axboe wrote:
> > >> > > >         > > > On Wed, Dec 20 2006, Jens Axboe wrote:
> > >> > > >         > > > > On Wed, Dec 20 2006, Jens Axboe wrote:
> > >> > > >         > > > > > Irk, do_pipe() needs to know what the input is,
> > >> > > >         obviously. Lemme add
> > >> > > >         > > > > > that as well.
> > >> > > >         > > > >
> > >> > > >         > > > > This has a better chance of working, still not
> > >tested
> > >> > > >         though. If you can
> > >> > > >         > > > > test, I'll commit it once we have it working.
> > >> > > >         > > >
> > >> > > >         > > > It works for me, just tested it. Patch committed.
> > >> > > >         > > >
> > >> > > >         > >
> > >> > > >         > > yes, works. thx.
> > >> > > >         > >
> > >> > > >         > > now the fifo will use a name pattern like foo. but
> > >regular
> > >> > > >         file will use
> > >> > > >         > > foo.blktrace.X and if you give full name, blkparse
> > >does
> > >> > > >         not report any
> > >> > > >         > > warning or error, just return 0 results. this drove me
> > >> > > >         nuts before i
> > >> > > >         > > read the code.
> > >> > > >         > >
> > >> > > >         > > [ [EMAIL PROTECTED] blktrace]$ ./blkparse 
> > >> > > > a.a.blktrace.0
> > >> > > >         > > WARNING: full file name given. Should give trace name
> > >foo,
> > >> > > >         > >         instead of file name foo.blktrace.x
> > >> > > >         >
> > >> > > >         > Better would be to just fix it up for the user, the
> > >current
> > >> > > >         setup is a
> > >> > > >         > little un-intuitive. Care to patch that up? :-)
> > >> > > >         >
> > >> > > >
> > >> > > >         are these what u want?
> > >> > > >
> > >> > > >         * user supplied a foo, we automatically match it with
> > >> > > >         foo.blktrace.X and
> > >> > > >         open.
> > >> > > >         * user supplied a foo.blktrace.X, we do not add extra
> > >> > > >         blktace.X and open
> > >> > > >         it directly.
> > >> > > >
> > >> > > >         then if user have foo.blktrace.0 and foo.blktrace.1,
> > >current
> > >> > > >         code works
> > >> > > >         when use "-i foo". then shall we support "-i
> > >foo.blktrace.0"
> > >> > > >         and open
> > >> > > >         foo.blktrace.1 automatically?
> > >> > > >
> > >> > > >
> > >> > > >         Perhaps, if user explicity supplies the name(s),  you
> > >should
> > >> > > >         open just that (those) file(s). May be you should open all
> > >> > > >         when the name is supplied as foo.blktrace.*
> > >> > >
> > >> > > key point here is not the implementation difficulty, but how we
> > >decide a
> > >> > > consistent rule. i agree with the rules u set, if i understand
> > >> > > correctly.
> > >> > >
> > >> > > * if "-", then read from stdin;
> > >> > > * if file name is foo.blktrace.*, then we try to open all;
> > >> > > * all other file name pattern, we open only _one_ file with _exact_
> > >file
> > >> > > name.
> > >> > >
> > >> > > See if others like this.
> > >> >
> > >> > I think that is the best approach, if the case where the full name is
> > >> > given we check and warn if other CPU files are there. It could just be
> > >a
> > >> > pilot error, and we should warn in that case.
> > >> >
> > >> > "You specified file foo.blktrace.0 and files from other CPUs also
> > >exist.
> > >> > blkparse will only read the given file, which may not be what you
> > >want.
> > >> > Use 'foo' as the filename to read all saved data."
> > >> >
> > >> > or something to that effect.
> > >>
> > >> ok. i will give it a try.
> > >
> > >On 2nd thought, is it _ever_ a good idea not to read all the files? The
> > >message will whiz by and nobody will ever see it, they will just get
> > >partial (and bad) data. So probably that case of giving foo.blktrace.x
> > >should just work like doing foo.
> > 
> > 
> > Not necessarily bad data.  When you are playing with HT on/off or adding and
> > removing processors, and if you accidentally use the same name foo this will
> > be useful.
> 
> That's really an obscure scenario though, I'd consider it many times
> more likely that someone will acidentally give a full file name than
> someone rerunning the same trace with less CPUs. It's a lot better to
> prevent accidental problems imho.
> 

agree, i prefer a clear interface with no obscure meaning or hidden
effect.


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