This patch set aims to improve the latencies of virtio-fs requests when the system is under high load, namely when the application's IO depth is greater than the size of the Virtio queue.
We found that the handling of -ENOMEM when enqueueing requests is inconsistent with other parts of the kernel (e.g. FUSE) and also obstructs optimizing the enqueueing behavior. It is important to first remove the -ENOMEM behavior as the new style of retrying virtio-fs requests in patch 2/2 is only correct in case of -ENOSPC. With -ENOMEM the failed enqueue might never be retried as there might not be another completion to trigger retrying the enqueue. Note that this patch series is a revival of my patch that was last discussed in the mailing list on 2023-08-16. Peter-Jan Gootzen (2): virtio-fs: let -ENOMEM bubble up or burst gently virtio-fs: improved request latencies when Virtio queue is full fs/fuse/virtio_fs.c | 40 ++++++++++++++++++++++------------------ 1 file changed, 22 insertions(+), 18 deletions(-) -- 2.34.1
