Am 13.02.2025 um 19:00 hat Stefan Hajnoczi geschrieben: > Implement --device virtio-scsi-pci,iothread-vq-mapping= support so that > virtqueues can be assigned to different IOThreads. This improves SMP guest > scalability where I/O-intensive applications can become bottlenecked on a > single IOThread. > > The following benchmark results show the effect of iothread-vq-mapping. fio > randread 4k iodepth=64 results from a 4 vCPU guest with an Intel P4800X SSD: > iothreads IOPS > ------------------------------ > 1 189576 > 2 312698 > 4 346744 > > The virtio-scsi device model and core SCSI emulation currently assume that > requests are processed in a single AioContext. This patch series goes about > modifying this as follows: > > scsi-disk: drop unused SCSIDiskState->bh field > dma: use current AioContext for dma_blk_io() > > Make dma-helpers.c support the QEMU multi-queue block layer by using > qemu_get_current_aio_context(). > > scsi: track per-SCSIRequest AioContext > scsi: introduce requests_lock > > Make the core SCSI emulation code support processing requests in multiple > AioContexts by protecting the per-SCSIDevice requests list. > > virtio-scsi: introduce event and ctrl virtqueue locks > virtio-scsi: protect events_dropped field > virtio-scsi: perform TMFs in appropriate AioContexts > > Make the virtio-scsi emulation code support processing requests in multiple > AioContexts. The event and ctrl virtqueues can interact with multiple > AioContexts. Especially the SCSI Task Management Functions (TMFs) handled by > the ctrl virtqueue need to be made thread-safe. > > virtio-blk: extract cleanup_iothread_vq_mapping() function > virtio-blk: tidy up iothread_vq_mapping functions > virtio: extract iothread-vq-mapping.h API > virtio-scsi: add iothread-vq-mapping parameter > > Port over the iothread-vq-mapping qdev property from virtio-blk to > virtio-scsi. > > virtio-scsi: handle ctrl virtqueue in main loop > > Simplify TMF handling now that there is no longer a single AioContext where > all > requests are processed. > > Stefan Hajnoczi (12): > scsi-disk: drop unused SCSIDiskState->bh field > dma: use current AioContext for dma_blk_io() > scsi: track per-SCSIRequest AioContext > scsi: introduce requests_lock > virtio-scsi: introduce event and ctrl virtqueue locks > virtio-scsi: protect events_dropped field > virtio-scsi: perform TMFs in appropriate AioContexts > virtio-blk: extract cleanup_iothread_vq_mapping() function > virtio-blk: tidy up iothread_vq_mapping functions > virtio: extract iothread-vq-mapping.h API > virtio-scsi: add iothread-vq-mapping parameter > virtio-scsi: handle ctrl virtqueue in main loop
Patches 1-10: Reviewed-by: Kevin Wolf <kw...@redhat.com>
