Messages in this thread Patch in this message | | | From | Salil Mehta <> | Subject | RE: [Intel-wired-lan] [PATCH V2 net] ice: Re-organizes reqstd/avail {R, T}XQ check/code for efficiency+readability | Date | Wed, 21 Apr 2021 08:08:00 +0000 |
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> From: Paul Menzel [mailto:pmenzel@molgen.mpg.de] > Sent: Wednesday, April 21, 2021 8:54 AM > > [CC: Remove Jeff, as email is rejected]
Yes, thanks for the reminder. I had noticed it earlier.
[...]
> >>> diff --git a/drivers/net/ethernet/intel/ice/ice_lib.c > b/drivers/net/ethernet/intel/ice/ice_lib.c > >>> index d13c7fc8fb0a..d77133d6baa7 100644 > >>> --- a/drivers/net/ethernet/intel/ice/ice_lib.c > >>> +++ b/drivers/net/ethernet/intel/ice/ice_lib.c > >>> @@ -161,12 +161,13 @@ static void ice_vsi_set_num_qs(struct ice_vsi *vsi, > u16 vf_id) > >>> > >>> switch (vsi->type) { > >>> case ICE_VSI_PF: > >>> - vsi->alloc_txq = min3(pf->num_lan_msix, > >>> - ice_get_avail_txq_count(pf), > >>> - (u16)num_online_cpus()); > >>> if (vsi->req_txq) { > >>> vsi->alloc_txq = vsi->req_txq; > >>> vsi->num_txq = vsi->req_txq; > >>> + } else { > >>> + vsi->alloc_txq = min3(pf->num_lan_msix, > >>> + ice_get_avail_txq_count(pf), > >>> + (u16)num_online_cpus()); > >>> } > >> > >> I am curious, did you check the compiler actually creates different > >> code, or did it notice the inefficiency by itself and optimized it already? > > > > I have not looked into that detail but irrespective of what compiler generates > > I would like to keep the code in a shape which is more efficient and more readable. > > > > I do understand in certain cases we have to do tradeoff between efficiency > > and readability but I do not see that here. > > I agree, as *efficiency* is mentioned several times, I assume it was > tested. Thank you for the clarification.
I mentioned inefficient because below code gets executed unnecessarily.
/** * ice_get_avail_q_count - Get count of queues in use * @pf_qmap: bitmap to get queue use count from * @lock: pointer to a mutex that protects access to pf_qmap * @size: size of the bitmap */ static u16 ice_get_avail_q_count(unsigned long *pf_qmap, struct mutex *lock, u16 size) { unsigned long bit; u16 count = 0;
mutex_lock(lock); for_each_clear_bit(bit, pf_qmap, size) count++; mutex_unlock(lock);
return count; }
/** * ice_get_avail_txq_count - Get count of Tx queues in use * @pf: pointer to an ice_pf instance */ u16 ice_get_avail_txq_count(struct ice_pf *pf) { return ice_get_avail_q_count(pf->avail_txqs, &pf->avail_q_mutex, pf->max_pf_txqs); }
> >>> pf->num_lan_tx = vsi->alloc_txq; > >>> @@ -175,12 +176,13 @@ static void ice_vsi_set_num_qs(struct ice_vsi *vsi, > u16 vf_id) > >>> if (!test_bit(ICE_FLAG_RSS_ENA, pf->flags)) { > >>> vsi->alloc_rxq = 1; > >>> } else { > >>> - vsi->alloc_rxq = min3(pf->num_lan_msix, > >>> - ice_get_avail_rxq_count(pf), > >>> - (u16)num_online_cpus()); > >>> if (vsi->req_rxq) { > >>> vsi->alloc_rxq = vsi->req_rxq; > >>> vsi->num_rxq = vsi->req_rxq; > >>> + } else { > >>> + vsi->alloc_rxq = min3(pf->num_lan_msix, > >>> + ice_get_avail_rxq_count(pf), > >>> + (u16)num_online_cpus()); > >>> } > >>> } > >>> > > > Kind regards, > > Paul
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