Date: Fri, 23 Oct 2015 15:46:42 +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: r289836 - head/sys/dev/xen/blkfront Message-ID: <201510231546.t9NFkggN020961@repo.freebsd.org>
next in thread | raw e-mail | index | archive | help
Author: royger Date: Fri Oct 23 15:46:42 2015 New Revision: 289836 URL: https://svnweb.freebsd.org/changeset/base/289836 Log: 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: r289834 Modified: head/sys/dev/xen/blkfront/blkfront.c Modified: head/sys/dev/xen/blkfront/blkfront.c ============================================================================== --- head/sys/dev/xen/blkfront/blkfront.c Fri Oct 23 15:40:44 2015 (r289835) +++ head/sys/dev/xen/blkfront/blkfront.c Fri Oct 23 15:46:42 2015 (r289836) @@ -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,
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?201510231546.t9NFkggN020961>