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X-Received-From: 2607:f8b0:4864:20::641 Subject: [Qemu-devel] [PATCH] block/nvme: optimize the performance of nvme driver based on vfio-pci X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Li Feng , Kevin Wolf , Fam Zheng , "open list:NVMe Block Driver" , "open list:All patches CC here" , Max Reitz Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) When the IO size is larger than 2 pages, we move the the pointer one by one in the pagelist, this is inefficient. This is a simple benchmark result: Before: $ qemu-io -c 'write 0 1G' nvme://0000:00:04.0/1 wrote 1073741824/1073741824 bytes at offset 0 1 GiB, 1 ops; 0:00:02.41 (424.504 MiB/sec and 0.4146 ops/sec) $ qemu-io -c 'read 0 1G' nvme://0000:00:04.0/1 read 1073741824/1073741824 bytes at offset 0 1 GiB, 1 ops; 0:00:02.03 (503.055 MiB/sec and 0.4913 ops/sec) After: $ qemu-io -c 'write 0 1G' nvme://0000:00:04.0/1 wrote 1073741824/1073741824 bytes at offset 0 1 GiB, 1 ops; 0:00:02.17 (471.517 MiB/sec and 0.4605 ops/sec) $ qemu-io -c 'read 0 1G' nvme://0000:00:04.0/1 = = = = 1 =E2=86=B5 read 1073741824/1073741824 bytes at offset 0 1 GiB, 1 ops; 0:00:01.94 (526.770 MiB/sec and 0.5144 ops/sec) Signed-off-by: Li Feng --- block/nvme.c | 16 ++++++---------- 1 file changed, 6 insertions(+), 10 deletions(-) diff --git a/block/nvme.c b/block/nvme.c index 29294038fc..982097b5b1 100644 --- a/block/nvme.c +++ b/block/nvme.c @@ -837,7 +837,7 @@ try_map: } =20 for (j =3D 0; j < qiov->iov[i].iov_len / s->page_size; j++) { - pagelist[entries++] =3D iova + j * s->page_size; + pagelist[entries++] =3D cpu_to_le64(iova + j * s->page_size); } trace_nvme_cmd_map_qiov_iov(s, i, qiov->iov[i].iov_base, qiov->iov[i].iov_len / s->page_size); @@ -850,20 +850,16 @@ try_map: case 0: abort(); case 1: - cmd->prp1 =3D cpu_to_le64(pagelist[0]); + cmd->prp1 =3D pagelist[0]; cmd->prp2 =3D 0; break; case 2: - cmd->prp1 =3D cpu_to_le64(pagelist[0]); - cmd->prp2 =3D cpu_to_le64(pagelist[1]);; + cmd->prp1 =3D pagelist[0]; + cmd->prp2 =3D pagelist[1]; break; default: - cmd->prp1 =3D cpu_to_le64(pagelist[0]); - cmd->prp2 =3D cpu_to_le64(req->prp_list_iova); - for (i =3D 0; i < entries - 1; ++i) { - pagelist[i] =3D cpu_to_le64(pagelist[i + 1]); - } - pagelist[entries - 1] =3D 0; + cmd->prp1 =3D pagelist[0]; + cmd->prp2 =3D cpu_to_le64(req->prp_list_iova + sizeof(uint64_t)); break; } trace_nvme_cmd_map_qiov(s, cmd, req, qiov, entries); --=20 2.11.0