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Re: [Qemu-devel] [RFC v2] qemu: Add virtio pmem device
From: |
Stefan Hajnoczi |
Subject: |
Re: [Qemu-devel] [RFC v2] qemu: Add virtio pmem device |
Date: |
Thu, 26 Apr 2018 14:24:06 +0100 |
User-agent: |
Mutt/1.9.2 (2017-12-15) |
On Wed, Apr 25, 2018 at 04:54:15PM +0530, Pankaj Gupta wrote:
> +static void virtio_pmem_flush(VirtIODevice *vdev, VirtQueue *vq)
> +{
> + VirtQueueElement *elem;
> + VirtIOPMEM *pmem = VIRTIO_PMEM(vdev);
> + HostMemoryBackend *backend = MEMORY_BACKEND(pmem->memdev);
> + int fd = memory_region_get_fd(&backend->mr);
> +
> + elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
> + if (!elem) {
> + return;
> + }
> + /* flush raw backing image */
> + fsync(fd);
fsync(2) is a blocking syscall. This can hang QEMU for an unbounded
amount of time.
Please do the fsync from a thread pool. See block/file-posix.c's
aio_worker() for an example.
> +static void virtio_pmem_get_config(VirtIODevice *vdev, uint8_t *config)
> +{
> + VirtIOPMEM *pmem = VIRTIO_PMEM(vdev);
> + struct virtio_pmem_config *pmemcfg = (struct virtio_pmem_config *)
> config;
> +
> + pmemcfg->start = pmem->start;
> + pmemcfg->size = pmem->size;
Endianness. Please use virtio_st*_p() instead.
> +#define VIRTIO_PMEM_PLUG 0
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- Re: [Qemu-devel] [RFC v2 2/2] pmem: device flush over VIRTIO, (continued)
[Qemu-devel] [RFC v2] qemu: Add virtio pmem device, Pankaj Gupta, 2018/04/25
Re: [Qemu-devel] [RFC v2] qemu: Add virtio pmem device, Eric Blake, 2018/04/25
Re: [Qemu-devel] [RFC v2] qemu: Add virtio pmem device,
Stefan Hajnoczi <=
Re: [Qemu-devel] [RFC v2] qemu: Add virtio pmem device, no-reply, 2018/04/26