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Re: [PATCH] vhost: reduce the set_mem_table call frenquency
From: |
Li Feng |
Subject: |
Re: [PATCH] vhost: reduce the set_mem_table call frenquency |
Date: |
Tue, 23 Aug 2022 15:12:15 +0800 |
Sorry, looks like I use the old qemu code, master has fix this issue.
Just ignore this patch.
> 2022年8月23日 下午1:38,Li Feng <fengli@smartx.com> 写道:
>
> If the vhost memory layout doesn't change, don't need to call the vhost
> backend.
> The set_mem_table is time consuming when sending to vhost-user backend.
>
> On aarch64, the edk2 uefi firmware will write the pflash which will
> trigger the vhost_commit hundreds of times.
>
> Signed-off-by: Li Feng <fengli@smartx.com>
> ---
> hw/virtio/vhost.c | 14 ++++++++++++++
> include/hw/virtio/vhost.h | 2 ++
> 2 files changed, 16 insertions(+)
>
> diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
> index f758f177bb..848d2f20d6 100644
> --- a/hw/virtio/vhost.c
> +++ b/hw/virtio/vhost.c
> @@ -523,6 +523,11 @@ static void vhost_commit(MemoryListener *listener)
> /* Rebuild the regions list from the new sections list */
> regions_size = offsetof(struct vhost_memory, regions) +
> dev->n_mem_sections * sizeof dev->mem->regions[0];
> + if (dev->mem && dev->started) {
> + g_free(dev->old_mem);
> + dev->old_mem = dev->mem;
> + dev->mem = NULL;
> + }
> dev->mem = g_realloc(dev->mem, regions_size);
> dev->mem->nregions = dev->n_mem_sections;
> used_memslots = dev->mem->nregions;
> @@ -542,6 +547,12 @@ static void vhost_commit(MemoryListener *listener)
> goto out;
> }
>
> + if (dev->old_mem && dev->regions_size == regions_size &&
> + memcmp(dev->mem, dev->old_mem, dev->regions_size) == 0) {
> + goto out;
> + }
> +
> + dev->regions_size = regions_size;
> for (i = 0; i < dev->mem->nregions; i++) {
> if (vhost_verify_ring_mappings(dev,
> (void *)(uintptr_t)dev->mem->regions[i].userspace_addr,
> @@ -1445,6 +1456,8 @@ int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
> hdev->mem = g_malloc0(offsetof(struct vhost_memory, regions));
> hdev->n_mem_sections = 0;
> hdev->mem_sections = NULL;
> + hdev->old_mem = NULL;
> + hdev->regions_size = 0;
> hdev->log = NULL;
> hdev->log_size = 0;
> hdev->log_enabled = false;
> @@ -1491,6 +1504,7 @@ void vhost_dev_cleanup(struct vhost_dev *hdev)
> }
> g_free(hdev->mem);
> g_free(hdev->mem_sections);
> + g_free(hdev->old_mem);
> if (hdev->vhost_ops) {
> hdev->vhost_ops->vhost_backend_cleanup(hdev);
> }
> diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h
> index a346f23d13..b1d7287099 100644
> --- a/include/hw/virtio/vhost.h
> +++ b/include/hw/virtio/vhost.h
> @@ -73,6 +73,8 @@ struct vhost_dev {
> MemoryListener memory_listener;
> MemoryListener iommu_listener;
> struct vhost_memory *mem;
> + struct vhost_memory *old_mem;
> + int regions_size;
> int n_mem_sections;
> MemoryRegionSection *mem_sections;
> int n_tmp_sections;
> --
> 2.37.2
>