Date: Mon, 9 Nov 2015 12:22:44 +0000 (UTC) From: =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= <royger@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r290611 - head/sys/dev/xen/blkfront Message-ID: <201511091222.tA9CMioB069828@repo.freebsd.org>
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Author: royger Date: Mon Nov 9 12:22:44 2015 New Revision: 290611 URL: https://svnweb.freebsd.org/changeset/base/290611 Log: xen-blkfront: add support for unmapped IO Using unmapped IO is really beneficial when running inside of a VM, since it avoids IPIs to other vCPUs in order to invalidate the mappings. This patch adds unmapped IO support to blkfront. The following tests results have been obtained when running on a Xen host without HAP: PVHVM 3165.84 real 6354.17 user 4483.32 sys PVHVM with unmapped IO 2099.46 real 4624.52 user 2967.38 sys This is because when running using shadow page tables TLB flushes and range invalidations are much more expensive, so using unmapped IO provides a very important performance boost. Sponsored by: Citrix Systems R&D MFC after: 2 weeks X-MFC-with: r290610 dev/xen/blkfront/blkfront.c: - Add and announce support for unmapped IO. Modified: head/sys/dev/xen/blkfront/blkfront.c Modified: head/sys/dev/xen/blkfront/blkfront.c ============================================================================== --- head/sys/dev/xen/blkfront/blkfront.c Mon Nov 9 12:19:58 2015 (r290610) +++ head/sys/dev/xen/blkfront/blkfront.c Mon Nov 9 12:22:44 2015 (r290611) @@ -293,8 +293,12 @@ xbd_queue_request(struct xbd_softc *sc, { int error; - error = bus_dmamap_load(sc->xbd_io_dmat, cm->cm_map, cm->cm_data, - cm->cm_datalen, xbd_queue_cb, cm, 0); + if (cm->cm_bp != NULL) + error = bus_dmamap_load_bio(sc->xbd_io_dmat, cm->cm_map, + cm->cm_bp, xbd_queue_cb, cm, 0); + else + error = bus_dmamap_load(sc->xbd_io_dmat, cm->cm_map, + cm->cm_data, cm->cm_datalen, xbd_queue_cb, cm, 0); if (error == EINPROGRESS) { /* * Maintain queuing order by freezing the queue. The next @@ -354,8 +358,6 @@ xbd_bio_command(struct xbd_softc *sc) } cm->cm_bp = bp; - cm->cm_data = bp->bio_data; - cm->cm_datalen = bp->bio_bcount; cm->cm_sector_number = (blkif_sector_t)bp->bio_pblkno; switch (bp->bio_cmd) { @@ -1009,7 +1011,7 @@ xbd_instance_create(struct xbd_softc *sc sc->xbd_disk->d_mediasize = sectors * sector_size; sc->xbd_disk->d_maxsize = sc->xbd_max_request_size; - sc->xbd_disk->d_flags = 0; + sc->xbd_disk->d_flags = DISKFLAG_UNMAPPED_BIO; if ((sc->xbd_flags & (XBDF_FLUSH|XBDF_BARRIER)) != 0) { sc->xbd_disk->d_flags |= DISKFLAG_CANFLUSHCACHE; device_printf(sc->xbd_dev,
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