Subject: Re: [PATCH v6 net-next 2/5] net: implement support for low latency socket polling

From: Eliezer Tamir <[email-masked]>
Date: Wed, 29 May 2013 17:01:38 +0300

On 29/05/2013 16:37, Eric Dumazet wrote:
> On Wed, 2013-05-29 at 09:39 +0300, Eliezer Tamir wrote:

>> +static inline unsigned long ll_end_time(void)
>> +{
>> +	return TSC_MHZ * ACCESS_ONCE(sysctl_net_ll_poll) + get_cycles();
>> +}
>
> This can overflow.
>
> Multiply is giving 32bits, as tsc_khz is an int, and sysctl_net_ll_poll
> is an int.
>
> unsigned long sysctl_net_ll_poll ?
OK

> Also, if we want this to work on i386, the correct type to use for
> ll_end_time(void) would be cycles_t

OK
I would be really surprised if someone uses this on an i386, but I guess 
you never know.

Thanks!
-Eliezer

------------------------------------------------------------------------------
Introducing AppDynamics Lite, a free troubleshooting tool for Java/.NET
Get 100% visibility into your production application - at no cost.
Code-level diagnostics for performance bottlenecks with <2% overhead
Download for free and get started troubleshooting in minutes.
http://p.sf.net/sfu/appdyn_d2d_ap1
_______________________________________________
E1000-devel mailing list
[email-masked]
https://lists.sourceforge.net/lists/listinfo/e1000-devel
To learn more about Intel&#174; Ethernet, visit http://communities.intel.com/community/wired