On Tue, Jan 09 2007, Vasily Tarasov wrote:
> Jens Axboe wrote:
> > On Thu, Dec 28 2006, Tom Zanussi wrote:
> >
> >> Hi,
> >>
> >> It looks like the documentation is wrong - from the blkparse code,
> >> apparently 'B' means 'Bounce', and is what's actually used instead of
> >> the 'W' the documentation has. 'Backmerge' according to the code is
> >> actually 'M', and is used instead of the 'B' the documentation has for
> >> that. There doesn't seem to be anything that uses 'front or back
> >> merge' as described for 'M' in the documentation. There also seems to
> >> be the same mixup in the formatting code.
> >>
> >> The patch below makes those changes according to my understanding of
> >> how they're actually used in the code...
> >>
> >
> > Tom, you are correct, the 'B' is a bounce and not a backmerge. Vasily,
> > you may want to look into your setup, bouncing is very harmful to io
> > performance.
> >
> > I've applied the patch, thanks!
> >
> >
> Hello,
>
> Tom, Jens, thanks for the answers, now blkparse output looks believable
> for me.
> However some places in the code to change were missed. The patch below adds
> needed changes.
>
> I will look at my configuration: why I have so much bounces, thanks.
>
> Sorry for my unforgivably slow reaction: we had 12 days off
> here due to New Year ;)
>
> Thanks,
> Vasily.
>
> --- ./README.orig 2007-01-09 12:57:16.000000000 +0300
> +++ ./README 2007-01-09 14:19:40.000000000 +0300
> @@ -109,13 +109,13 @@ $ blkparse -i <input> [ -o <output> ] [
> -F Format specification. The individual specifiers are:
>
> A - Remap
> - B - Back merge
> + B - Bounce
> C - Complete
> D - Issue
> + M - Back merge
> F - Front merge
> G - Get request
> I - Insert
> - M - Both front and back merge
> P - Plug
> Q - Queue
> R - Requeue
> --- ./blkparse_fmt.c.orig 2007-01-09 12:57:16.000000000 +0300
> +++ ./blkparse_fmt.c 2007-01-09 14:09:55.000000000 +0300
> @@ -49,14 +49,7 @@ int add_format_spec(char *option)
> return 1;
> }
>
> - /*
> - * Set both merges (front and back)
> - */
> - if (spec == 'M') {
> - override_format['B'] = strdup(option);
> - override_format['M'] = strdup(option);
> - } else
> - override_format[spec] = strdup(option);
> + override_format[spec] = strdup(option);
>
> return 0;
> }
Looks good, applied.
--
Jens Axboe
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