On Wed, 2017-02-15 at 15:59 +0200, Saeed Mahameed wrote: > can the tasklet run on a different core ?
No. tasklets are scheduled on local cpu, like softirqs in general. They are not migrated, unless cpu is removed (hotplug) > > the point is that if the EQ is full of CQEs from different CQs you would > do the " kick = list_empty(&tasklet_ctx->list);" test per empty CQ > list rather than once at the end. > > in mlx4_en case, you have only two CQs on each EQ but in RoCE/IB you > can have as many CQs as you want. list_empty() before one list_add_tail() is a single instruction. By doing this right before manipulating the list, it comes with a zero cache line penalty. While if you do it at the wrong place, it incurs one extra cache line miss. This extra tasklet invocations can cost 3 % of cpu cycles.
