Hi Francois,
Resurrecting an old thread.
On 06/14/2013 03:49 AM, Francois Romieu wrote:
>> +static irqreturn_t arc_emac_intr(int irq, void *dev_instance)
>> > +{
>> > + struct net_device *ndev = dev_instance;
>> > + struct arc_emac_priv *priv = netdev_priv(ndev);
>> > + struct net_device_stats *stats = &priv->stats;
>> > + unsigned int status;
>> > +
>> > + status = arc_reg_get(priv, R_STATUS);
>> > + status &= ~MDIO_MASK;
>> > +
>> > + /* Reset all flags except "MDIO complete"*/
>> > + arc_reg_set(priv, R_STATUS, status);
>> > +
>> > + if (status & RXINT_MASK) {
>> > + if (likely(napi_schedule_prep(&priv->napi))) {
>> > + arc_reg_clr(priv, R_ENABLE, RXINT_MASK);
>> > + __napi_schedule(&priv->napi);
>> > + }
>> > + }
>> > +
>> > + if (status & TXINT_MASK) {
> You may consider moving everything into the napi poll handler.
I has to revisit this now-mainlined driver recently for fixing a bug. Per your
suggestion above, the TX BD reclaim was moved from interrupt context to NAPI
context. I was wondering if that is the right thing to do (I'm not a networking
expert but have worked on this driver heavily before it was mainlined by
Alexey).
In case of large burst transfers by networking stack (say a large file copy over
NFS) will it not delay the TX BD reclaim possibly dropping more packets.
Ofcourse
doing this requires enabling Tx interrupts which adds to overall cost from a
system perspective, but assuming the controller can coalesce the Tx interrupts,
will it not be better.
I did a quick hack to move the TX reclaim in intr path and it seems to be doing
slightly better than the current code - so the advantages are not sky high, but
I
want to understand the implications nevertheless.
TIA,
-Vineet
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