Re: [PATCH v5 02/10] fwd: Added cache table for ARP/NDP contents

[Jon Maloy <jmaloy@redhat.com>]

On 2025-09-07 22:42, David Gibson wrote:
> On Fri, Sep 05, 2025 at 10:11:46PM -0400, Jon Maloy wrote:
>> We add a cache table to keep partial contents of the kernel ARP/NDP

[...]

>> +	return mac_undefined(e->mac);
>> +}
>> +
>> +/**
>> + * mac_entry_expired() - Check if a cache entry has expired
>> + * @e:		Cache entry
>> + *
>> + * Return: True if the entry has expired, false otherwise
>> + */
>> +static bool mac_entry_expired(const struct mac_cache_entry *e)
>> +{
>> +	struct timespec now;
>> +
>> +	clock_gettime(CLOCK_MONOTONIC, &now);
> 
> Mostly we try to keep to a single clock_gettime() call per epoll
> cycle, passing 'now' down to the things we call there.
> 
>> +	return timespec_before(&e->expiry, &now);
>> +}

Passing this value along the whole call chain just for the unlikely case 
that we may need it here seems like a bad idea, especially since the 
performance gain is minimal.

It would make some sense if we add it to the context struct or even as a 
global variable the set it in the main loop, and pass it along that way. 
What do you think?
///jon