Messages in this thread Patch in this message | | | Subject | Re: [PATCH] RDMA/core: reduce IB_POLL_BATCH constant | From | Max Gurtovoy <> | Date | Wed, 28 Feb 2018 00:15:56 +0200 |
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On 2/28/2018 12:09 AM, Jason Gunthorpe wrote: > On Thu, Feb 22, 2018 at 05:39:09PM +0200, Sagi Grimberg wrote: >> >>>> The only reason why I added this array on-stack was to allow consumers >>>> that did not use ib_alloc_cq api to call it, but that seems like a >>>> wrong decision when thinking it over again (as probably these users >>>> did not set the wr_cqe correctly). >>>> >>>> How about we make ib_process_cq_direct use the cq wc array and add >>>> a WARN_ON statement (and fail it gracefully) if the caller used this >>>> API without calling ib_alloc_cq? >>> >>> but we tried to avoid cuncurrent access to cq->wc. >> >> Not sure its a valid use-case. But if there is a compelling >> reason to keep it as is, then we can do smaller on-stack >> array. > > Did we come to a conclusion what to do here?
guys, what do you think about the following solution (untested):
diff --git a/drivers/infiniband/core/cq.c b/drivers/infiniband/core/cq.c index bc79ca8..59d2835 100644 --- a/drivers/infiniband/core/cq.c +++ b/drivers/infiniband/core/cq.c @@ -17,6 +17,7 @@
/* # of WCs to poll for with a single call to ib_poll_cq */ #define IB_POLL_BATCH 16 +#define IB_POLL_BATCH_DIRECT 8
/* # of WCs to iterate over before yielding */ #define IB_POLL_BUDGET_IRQ 256 @@ -25,17 +26,25 @@ #define IB_POLL_FLAGS \ (IB_CQ_NEXT_COMP | IB_CQ_REPORT_MISSED_EVENTS)
-static int __ib_process_cq(struct ib_cq *cq, int budget, struct ib_wc *poll_wc) +static int __ib_process_cq(struct ib_cq *cq, int budget, struct ib_wc *poll_wc, + int batch) { - int i, n, completed = 0; - struct ib_wc *wcs = poll_wc ? : cq->wc; - + int i, n, ib_poll_batch, completed = 0; + struct ib_wc *wcs; + + if (poll_wc) { + wcs = poll_wc; + ib_poll_batch = batch; + } else { + wcs = cq->wc; + ib_poll_batch = IB_POLL_BATCH; + } /* * budget might be (-1) if the caller does not * want to bound this call, thus we need unsigned * minimum here. */ - while ((n = ib_poll_cq(cq, min_t(u32, IB_POLL_BATCH, + while ((n = ib_poll_cq(cq, min_t(u32, ib_poll_batch, budget - completed), wcs)) > 0) { for (i = 0; i < n; i++) { struct ib_wc *wc = &wcs[i]; @@ -48,7 +57,7 @@ static int __ib_process_cq(struct ib_cq *cq, int budget, struct ib_wc *poll_wc)
completed += n;
- if (n != IB_POLL_BATCH || + if (n != ib_poll_batch || (budget != -1 && completed >= budget)) break; } @@ -72,9 +81,9 @@ static int __ib_process_cq(struct ib_cq *cq, int budget, struct ib_wc *poll_wc) */ int ib_process_cq_direct(struct ib_cq *cq, int budget) { - struct ib_wc wcs[IB_POLL_BATCH]; + struct ib_wc wcs[IB_POLL_BATCH_DIRECT];
- return __ib_process_cq(cq, budget, wcs); + return __ib_process_cq(cq, budget, wcs, IB_POLL_BATCH_DIRECT); } EXPORT_SYMBOL(ib_process_cq_direct);
@@ -88,7 +97,7 @@ static int ib_poll_handler(struct irq_poll *iop, int budget) struct ib_cq *cq = container_of(iop, struct ib_cq, iop); int completed;
- completed = __ib_process_cq(cq, budget, NULL); + completed = __ib_process_cq(cq, budget, NULL, 0); if (completed < budget) { irq_poll_complete(&cq->iop); if (ib_req_notify_cq(cq, IB_POLL_FLAGS) > 0) @@ -108,7 +117,7 @@ static void ib_cq_poll_work(struct work_struct *work) struct ib_cq *cq = container_of(work, struct ib_cq, work); int completed;
- completed = __ib_process_cq(cq, IB_POLL_BUDGET_WORKQUEUE, NULL); + completed = __ib_process_cq(cq, IB_POLL_BUDGET_WORKQUEUE, NULL, 0); if (completed >= IB_POLL_BUDGET_WORKQUEUE || ib_req_notify_cq(cq, IB_POLL_FLAGS) > 0) queue_work(ib_comp_wq, &cq->work);
> > Jason >
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