On Fri, Aug 03, 2018 at 08:04:06PM +0000, Justin Hibbits wrote: > 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 What is the purpose of this call ? It is useless without paired read barrier. So where is the reciprocal rmb() ?
This call is almost certainly wrong on x86. > + > 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); > } > _______________________________________________ svn-src-all@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
