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  1. Oct 22, 2009
    • Christian Borntraeger's avatar
      virtio: let header files include virtio_ids.h · e95646c3
      Christian Borntraeger authored
      
      Rusty,
      
      commit 3ca4f5ca
          virtio: add virtio IDs file
      moved all device IDs into a single file. While the change itself is
      a very good one, it can break userspace applications. For example
      if a userspace tool wanted to get the ID of virtio_net it used to
      include virtio_net.h. This does no longer work, since virtio_net.h
      does not include virtio_ids.h.
      This patch moves all "#include <linux/virtio_ids.h>" from the C
      files into the header files, making the header files compatible with
      the old ones.
      
      In addition, this patch exports virtio_ids.h to userspace.
      
      CC: Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp>
      Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
      Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
      e95646c3
    • Christoph Hellwig's avatar
      virtio_blk: revert QUEUE_FLAG_VIRT addition · f8b12e51
      Christoph Hellwig authored
      It seems like the addition of QUEUE_FLAG_VIRT caueses major performance
      regressions for Fedora users:
      
      	https://bugzilla.redhat.com/show_bug.cgi?id=509383
      	https://bugzilla.redhat.com/show_bug.cgi?id=505695
      
      
      
      while I can't reproduce those extreme regressions myself I think the flag
      is wrong.
      
      Rationale:
      
        QUEUE_FLAG_VIRT expands to QUEUE_FLAG_NONROT which casus the queue
        unplugged immediately.  This is not a good behaviour for at least
        qemu and kvm where we do have significant overhead for every
        I/O operations.  Even with all the latested speeups (native AIO,
        MSI support, zero copy) we can only get native speed for up to 128kb
        I/O requests we already are down to 66% of native performance for 4kb
        requests even on my laptop running the Intel X25-M SSD for which the
        QUEUE_FLAG_NONROT was designed.
        If we ever get virtio-blk overhead low enough that this flag makes
        sense it should only be set based on a feature flag set by the host.
      
      Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
      Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
      f8b12e51
  2. Oct 16, 2009
  3. Oct 15, 2009
  4. Oct 14, 2009
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