W dniu 08.12.2021 o 19:54, Chris Murphy pisze: > Hi, > > I'm trying to help progress a kernel regression hitting Fedora > infrastructure in which dozens of VMs run concurrently to execute QA > testing. The problem doesn't happen immediately, but all the VM's get > stuck and then any new process also gets stuck, so extracting > information from the system has been difficult and there's not a lot > to go on, but this is what I've got so far. Does qemu there have this fix? https://github.com/qemu/qemu/commit/cc071629539dc1f303175a7e2d4ab854c0a8b20f block: introduce max_hw_iov for use in scsi-generic 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. -- Arkadiusz Miśkiewicz, arekm / ( maven.pl | pld-linux.org )
