Date: Thu, 14 Oct 2021 14:45:36 GMT From: Warner Losh <imp@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: 2ec165e3f065 - main - nvme: Reduce traffic to the doorbell register Message-ID: <202110141445.19EEja1F027333@gitrepo.freebsd.org>
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The branch main has been updated by imp: URL: https://cgit.FreeBSD.org/src/commit/?id=2ec165e3f065217ae8d54a2a8235fe1f219805ea commit 2ec165e3f065217ae8d54a2a8235fe1f219805ea Author: Warner Losh <imp@FreeBSD.org> AuthorDate: 2021-10-14 14:44:37 +0000 Commit: Warner Losh <imp@FreeBSD.org> CommitDate: 2021-10-14 14:44:37 +0000 nvme: Reduce traffic to the doorbell register Reduce traffic to doorbell register when processing multiple completion events at once. Only write it at the end of the loop after we've processed everything (assuming we found at least one completion, even if that completion wasn't valid). Sponsored by: Netflix Reviewed by: mav Differential Revision: https://reviews.freebsd.org/D32470 --- sys/dev/nvme/nvme_qpair.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/sys/dev/nvme/nvme_qpair.c b/sys/dev/nvme/nvme_qpair.c index 6669eeee6613..54718492ff09 100644 --- a/sys/dev/nvme/nvme_qpair.c +++ b/sys/dev/nvme/nvme_qpair.c @@ -629,10 +629,10 @@ nvme_qpair_process_completions(struct nvme_qpair *qpair) else tr = NULL; + done++; if (tr != NULL) { nvme_qpair_complete_tracker(tr, &cpl, ERROR_PRINT_ALL); qpair->sq_head = cpl.sqhd; - done++; } else if (!in_panic) { /* * A missing tracker is normally an error. However, a @@ -664,10 +664,13 @@ nvme_qpair_process_completions(struct nvme_qpair *qpair) atomic_store_rel_int(&qpair->cq_head, 0); /* 2 */ qpair->phase = !qpair->phase; /* 3 */ } + } + if (done != 0) { bus_space_write_4(qpair->ctrlr->bus_tag, qpair->ctrlr->bus_handle, qpair->cq_hdbl_off, qpair->cq_head); } + return (done != 0); }
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