Hi Jisheng, On mer., août 29 2018, Jisheng Zhang <[email protected]> wrote:
> In the loop of mvneta_tx_done_gbe(), we call the smp_processor_id() > each time, move the call out of the loop to optimize the code a bit. > > Before the patch, the loop looks like(under arm64): > > ldr x1, [x29,#120] > ... > ldr w24, [x1,#36] > ... > bl 0 <_raw_spin_lock> > str w24, [x27,#132] > ... > > After the patch, the loop looks like(under arm64): > > ... > bl 0 <_raw_spin_lock> > str w23, [x28,#132] > ... > where w23 is loaded so be ready before the loop. > > From another side, mvneta_tx_done_gbe() is called from mvneta_poll() > which is in non-preemptible context, so it's safe to call the > smp_processor_id() function once. This improvement should go to net-next. Besides this patch looks nice: Reviewed-by: Gregory CLEMENT <[email protected]> Thanks, Gregory > > Signed-off-by: Jisheng Zhang <[email protected]> > --- > drivers/net/ethernet/marvell/mvneta.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/net/ethernet/marvell/mvneta.c > b/drivers/net/ethernet/marvell/mvneta.c > index 7d98f7828a30..62e81e267e13 100644 > --- a/drivers/net/ethernet/marvell/mvneta.c > +++ b/drivers/net/ethernet/marvell/mvneta.c > @@ -2507,12 +2507,13 @@ static void mvneta_tx_done_gbe(struct mvneta_port > *pp, u32 cause_tx_done) > { > struct mvneta_tx_queue *txq; > struct netdev_queue *nq; > + int cpu = smp_processor_id(); > > while (cause_tx_done) { > txq = mvneta_tx_done_policy(pp, cause_tx_done); > > nq = netdev_get_tx_queue(pp->dev, txq->id); > - __netif_tx_lock(nq, smp_processor_id()); > + __netif_tx_lock(nq, cpu); > > if (txq->count) > mvneta_txq_done(pp, txq); > -- > 2.18.0 > -- Gregory Clement, Bootlin Embedded Linux and Kernel engineering http://bootlin.com
