Hi Crystal,
On 4/4/23 12:04, Sean Anderson wrote:
> On 4/4/23 11:33, Crystal Wood wrote:
>> On Tue, 2023-04-04 at 10:55 -0400, Sean Anderson wrote:
>>
>>> @@ -1456,11 +1456,11 @@ static void tqm_congestion_task(struct work_struct
>>> *work)
>>> union qm_mc_result *mcr;
>>> struct qman_cgr *cgr;
>>>
>>> - spin_lock_irq(&p->cgr_lock);
>>> + raw_spin_lock_irq(&p->cgr_lock);
>>> qm_mc_start(&p->p);
>>> qm_mc_commit(&p->p, QM_MCC_VERB_QUERYCONGESTION);
>>> if (!qm_mc_result_timeout(&p->p, &mcr)) {
>>> - spin_unlock_irq(&p->cgr_lock);
>>> + raw_spin_unlock_irq(&p->cgr_lock);
>>
>> qm_mc_result_timeout() spins with a timeout of 10 ms which is very
>> inappropriate for a raw lock. What is the actual expected upper bound?
>
> Hm, maybe we can move this qm_mc stuff outside cgr_lock? In most other
> places they're called without cgr_lock, which implies that its usage
> here is meant to synchronize against some other function.
Do you have any suggestions here? I think this should really be handled
in a follow-up patch. If you think this code is waiting too long in a raw
spinlock, the existing code can wait just as long with IRQs disabled.
This patch doesn't change existing system responsiveness.
--Sean
>>> dev_crit(p->config->dev, "QUERYCONGESTION timeout\n");
>>> qman_p_irqsource_add(p, QM_PIRQ_CSCI);
>>> return;
>>> @@ -1476,7 +1476,7 @@ static void qm_congestion_task(struct work_struct
>>> *work)
>>> list_for_each_entry(cgr, &p->cgr_cbs, node)
>>> if (cgr->cb && qman_cgrs_get(&c, cgr->cgrid))
>>> cgr->cb(p, cgr, qman_cgrs_get(&rr, cgr->cgrid));
>>> - spin_unlock_irq(&p->cgr_lock);
>>> + raw_spin_unlock_irq(&p->cgr_lock);
>>> qman_p_irqsource_add(p, QM_PIRQ_CSCI);
>>> }
>>
>> The callback loop is also a bit concerning...
>
> The callbacks (in .../dpaa/dpaa_eth.c and .../caam/qi.c) look OK. The
> only thing which might take a bit is dpaa_eth_refill_bpools, which
> allocates memory (from the atomic pool).
>
> --Sean
