06.02.2018 22:02, Eric Blake wrote:
On 02/06/2018 12:06 PM, Vladimir Sementsov-Ogievskiy wrote:
06.02.2018 18:50, Eric Blake wrote:
On 02/06/2018 08:07 AM, Vladimir Sementsov-Ogievskiy wrote:
Set (and clear) histogram through new command
block-latency-histogram-set and show new statistics in
query-blockstats results.
The commit message mentioned that you can set and clear histogram
tracking; how does this interface let you clear things? By passing
a 0-length latency array? If you violate the constraint (pass
non-ascending points, for example), does the previous latency map
get wiped out or is it still preserved unchanged?
On error nothing is changed.
By "clear" I mean zeroing statistics, not removing the whole
histogram. And to zero statistics you can call set with the same
latency array.
There is no way to remove histogram at all.. We can add
block-latency-histogram-unset later if needed.
Maybe "set (or restart) histogram collection points" might read
better? I also don't think we need a new command; if you make
'latency' optional, then omitting it can serve to stop collecting
statistics altogether, without needing a new command (then again, if
you do that, now the command is used to "set, restart, and clear
histogram collection").
I like the idea, will do.
--
Best regards,
Vladimir
