Re: [PATCH] net: tcp: Fix a PTO timing granularity issue

[Ido Yariv]

Hi Eric,

On Wed, May 27, 2015 at 07:56:25AM -0700, Eric Dumazet wrote:
> On Wed, 2015-05-27 at 10:40 -0400, Ido Yariv wrote:
> 
> > HZ=100 is used on some embedded platforms, so it's still something we
> > have to deal with unfortunately..
> > 
> > Since the '2' here is a lower bound, and msecs_to_jiffies(10) will
> > return values greater than 2 for HZ>100 anyway, always ensuring the
> > 2 jiffies lower bound shouldn't impact the behavior when HZ=1000.
> > 
> > However, as far as I can tell, comparing msecs_to_jiffies(10) to 2, or
> > comparing the whole timeout to 2 doesn't make much difference, since
> > msecs_to_jiffies isn't inlined.
> > 
> > In other words, keeping the #if shouldn't make much difference in behavior,
> > but will save the small comparison.
> 
> Yes, I guess David point is to have a macro in include/linux/tcp.h so
> that we can have a nice comment, and not having #if ... in a C file.
> 
> Maybe other timers in TCP need the same care (I am not asking you to
> find them, but having a macro would ease things perhaps)

Something along the lines of the patch below?

Thanks,
Ido.