Author: jhibbits Date: Fri Aug 3 20:04:06 2018 New Revision: 337273 URL: https://svnweb.freebsd.org/changeset/base/337273
Log: nvme(4): Add bus_dmamap_sync() at the end of the request path Summary: Some architectures, in this case powerpc64, need explicit synchronization barriers vs device accesses. Prior to this change, when running 'make buildworld -j72' on a 18-core (72-thread) POWER9, I would see controller resets often. With this change, I don't see these resets messages, though another tester still does, for yet to be determined reasons, so this may not be a complete fix. Additionally, I see a ~5-10% speed up in buildworld times, likely due to not needing to reset the controller. Reviewed By: jimharris Differential Revision: https://reviews.freebsd.org/D16570 Modified: head/sys/dev/nvme/nvme_qpair.c Modified: head/sys/dev/nvme/nvme_qpair.c ============================================================================== --- head/sys/dev/nvme/nvme_qpair.c Fri Aug 3 19:24:04 2018 (r337272) +++ head/sys/dev/nvme/nvme_qpair.c Fri Aug 3 20:04:06 2018 (r337273) @@ -401,9 +401,13 @@ nvme_qpair_complete_tracker(struct nvme_qpair *qpair, req->retries++; nvme_qpair_submit_tracker(qpair, tr); } else { - if (req->type != NVME_REQUEST_NULL) + if (req->type != NVME_REQUEST_NULL) { + bus_dmamap_sync(qpair->dma_tag_payload, + tr->payload_dma_map, + BUS_DMASYNC_POSTREAD | BUS_DMASYNC_POSTWRITE); bus_dmamap_unload(qpair->dma_tag_payload, tr->payload_dma_map); + } nvme_free_request(req); tr->req = NULL; @@ -487,6 +491,8 @@ nvme_qpair_process_completions(struct nvme_qpair *qpai */ return (false); + bus_dmamap_sync(qpair->dma_tag, qpair->queuemem_map, + BUS_DMASYNC_POSTREAD | BUS_DMASYNC_POSTWRITE); while (1) { cpl = qpair->cpl[qpair->cq_head]; @@ -828,7 +834,16 @@ nvme_qpair_submit_tracker(struct nvme_qpair *qpair, st if (++qpair->sq_tail == qpair->num_entries) qpair->sq_tail = 0; + bus_dmamap_sync(qpair->dma_tag, qpair->queuemem_map, + BUS_DMASYNC_PREREAD | BUS_DMASYNC_PREWRITE); +#ifndef __powerpc__ + /* + * powerpc's bus_dmamap_sync() already includes a heavyweight sync, but + * no other archs do. + */ wmb(); +#endif + nvme_mmio_write_4(qpair->ctrlr, doorbell[qpair->id].sq_tdbl, qpair->sq_tail); @@ -879,6 +894,8 @@ nvme_payload_map(void *arg, bus_dma_segment_t *seg, in tr->req->cmd.prp2 = 0; } + bus_dmamap_sync(tr->qpair->dma_tag_payload, tr->payload_dma_map, + BUS_DMASYNC_PREREAD | BUS_DMASYNC_PREWRITE); nvme_qpair_submit_tracker(tr->qpair, tr); } _______________________________________________ [email protected] mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "[email protected]"
