Le mardi 13 décembre 2011 à 04:00 +0100, Richard Cochran a écrit :
> This commit removes the legacy timecompare code from the igb driver and
> offers a tunable PHC instead.
>
> Signed-off-by: Richard Cochran <[email protected]>
> ---
> +void igb_systim_to_hwtstamp(struct igb_adapter *adapter,
> + struct skb_shared_hwtstamps *hwtstamps,
> + u64 systim)
> +{
> + u64 ns;
> + unsigned long flags;
> + unsigned int shift;
> + int msb_set;
> +
> + switch (adapter->hw.mac.type) {
> + case e1000_i350:
> + case e1000_82580:
> + shift = OFL_SHIFT_82580;
> + msb_set = (systim >> 32) & SYSTIMH_MSB_82580;
> + break;
> + case e1000_82576:
> + shift = OFL_SHIFT_82576;
> + msb_set = (systim >> 32) & SYSTIMH_MSB_82576;
> + break;
> + default:
> + return;
> + }
> +
> + spin_lock_irqsave(&adapter->tmreg_lock, flags);
> +
> + ns = igb_overflow_get(adapter, systim, msb_set, shift);
> +
> + spin_unlock_irqrestore(&adapter->tmreg_lock, flags);
> +
> + memset(hwtstamps, 0, sizeof(*hwtstamps));
> + hwtstamps->hwtstamp = ns_to_ktime(ns);
> +}
Adding a (shared) spinlock on a multiqueue device is source of extra
delay (because of extra cache line trafic), I guess.
It seems current code doesnt need a spinlock, maybe it was a bug ?
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