Re: vprintf performance

[Pádraig Brady]

Sorry, just getting back to this now...

To recap, od using xprintf gives this throughput:
$ timeout 2 od -Ax -tx1z -v /dev/zero | pv >/dev/null # 1.58MB/s

There was lots of heap interaction going on,
and by using the attached patch (only illustrative, may leak,
is not thread safe, ...) to cache the PRINTF_PARSE result
it increases the throughput to 5.8MB/s

The rest of the time seems to be lost through the subsequent
call to snprintf, and I'm not sure how we can significantly improve that.
If we s/xprintf/printf/ in od.c for comparison, we get 10.7MB/s.

cheers,
Pádraig.

vasnprintf-cache-alloc.diff
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