Re: [PATCH net-next 3/3] ptp: idt82p33: optimize _idt82p33_adjfine

From: Richard Cochran
Date: Thu Nov 05 2020 - 12:02:10 EST


On Thu, Nov 05, 2020 at 02:35:56AM +0200, Vladimir Oltean wrote:
> On the other hand and with all due respect, saying that it may have been
> 'buggy on some archs back in the day' and then not bringing any evidence
> is a bit of a strange claim to make.

You're right. I made the effort to look back into the days of v3.0,
and the only thing I could find is that the 32 bit implementation of
div_s64 does extra operations and invokes an additional function call.
But the difference in performance, if any, is probably not very large.

> I am actively using div_s64 in drivers/net/dsa/sja1105/sja1105_ptp.c
> successfully on arm and arm64.

Yeah, I see div_s64 has found its way into the ntp code, too, so it
must be fine.

Thanks,
Richard