Re: [PATCH for-4.18 4/5] xenalyze: Fix interrupt EIP reporting

[Anthony PERARD <anthony.perard@xxxxxxxxxx>]

On Mon, Oct 09, 2023 at 01:51:36PM +0100, George Dunlap wrote:
> EIP lists are generalized across several use cases.  For many of them,
> it make sense to have a cycle per sample; but not really for interrupt
> EIP lists.  For this reason, it normally just passes 0 as for the tsc
> value, which will in turn down at the bottom of update_cycles(),
> update only the summary.event_count, but nothing else.
> 
> The dump_eip() function attempted to handle this by calling the generic
> cycle print handler if the summary contained *any* cycles, and by collecting
> and printing its own stats, based solely on counts, if not.
> 
> Unfortunately, it used the wrong element for this: it collected the
> total from samples.count rather samples.event_count; in the case that
> there are no cycles, this will always be zero.  It then divided by
> this zero value.  This results in output that looked like this:
> 
> ```
>   ffff89d29656                                             :        0  -nan%
>   ffff89d298b6                                             :        0  -nan%
>   ffff89d298c0                                             :        0  -nan%
> ```
> 
> It's better than nothing, but a lot less informative than one would
> like.
> 
> Use event_count rather than count for collecting the total, and the
> reporting when there are no cycles in the summary information.  This results
> in output that looks like this:
> 
> ```
>    ffff89d29656                                             :        2  1.21%
>    ffff89d298b6                                             :        1  0.61%
>    ffff89d298c0                                             :        1  0.61%
> ```
> 
> Signed-off-by: George Dunlap <george.dunlap@xxxxxxxxx>

Acked-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>

Thanks,

-- 
Anthony PERARD