cc07162953
Linux limits the size of iovecs to 1024 (UIO_MAXIOV in the kernel
sources, IOV_MAX in POSIX). Because of this, on some host adapters
requests with many iovecs are rejected with -EINVAL by the
io_submit() or readv()/writev() system calls.
In fact, the same limit applies to SG_IO as well. To fix both the
EINVAL and the possible performance issues from using fewer iovecs
than allowed by Linux (some HBAs have max_segments as low as 128),
introduce a separate entry in BlockLimits to hold the max_segments
value from sysfs. This new limit is used only for SG_IO and clamped
to bs->bl.max_iov anyway, just like max_hw_transfer is clamped to
bs->bl.max_transfer.
Reported-by: Halil Pasic <pasic@linux.ibm.com>
Cc: Hanna Reitz <hreitz@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>
Cc: qemu-block@nongnu.org
Cc: qemu-stable@nongnu.org
Fixes:
|
||
|---|---|---|
| .. | ||
| accel-ops.h | ||
| arch_init.h | ||
| balloon.h | ||
| block-backend.h | ||
| blockdev.h | ||
| cpu-throttle.h | ||
| cpu-timers.h | ||
| cpus.h | ||
| cryptodev-vhost-user.h | ||
| cryptodev-vhost.h | ||
| cryptodev.h | ||
| device_tree.h | ||
| dma.h | ||
| dump-arch.h | ||
| dump.h | ||
| hax.h | ||
| hostmem.h | ||
| hvf_int.h | ||
| hvf.h | ||
| hw_accel.h | ||
| iothread.h | ||
| kvm_int.h | ||
| kvm.h | ||
| memory_mapping.h | ||
| numa.h | ||
| nvmm.h | ||
| os-posix.h | ||
| os-win32.h | ||
| qtest.h | ||
| replay.h | ||
| reset.h | ||
| rng-random.h | ||
| rng.h | ||
| runstate-action.h | ||
| runstate.h | ||
| seccomp.h | ||
| sev.h | ||
| sysemu.h | ||
| tcg.h | ||
| tpm_backend.h | ||
| tpm_util.h | ||
| tpm.h | ||
| vhost-user-backend.h | ||
| watchdog.h | ||
| whpx.h | ||
| xen-mapcache.h | ||
| xen.h | ||