On 03/02/2016 13:34, Gonglei (Arei) wrote:
> Hi,
>
>> Subject: [Qemu-devel] [PATCH 07/10] virtio: combine the read of a descriptor
>>
>> Compared to vring, virtio has a performance penalty of 10%. Fix it
>> by combining all the reads for a descriptor in a single address_space_read
>> call. This also simplifies the code nicely.
>>
>> Reviewed-by: Cornelia Huck <cornelia.h...@de.ibm.com>
>> Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
>> ---
>> hw/virtio/virtio.c | 86
>> ++++++++++++++++++++++--------------------------------
>> 1 file changed, 35 insertions(+), 51 deletions(-)
>>
>
> Unbelievable! After applying this patch, the virtio-crypto speed can attach
> 74MB/sec, host
> Cpu overhead is 180% (the main thread 100% and vcpu threads 80%)
The three patches from Vincenzo will help too. What was it like before?
Also, are you using ioeventfd or dataplane? virtio-crypto sounds like
something that could be very easily run outside the "big QEMU lock".
Paolo
> Testing AES-128-CBC cipher:
> Encrypting in chunks of 256 bytes: done. 371.94 MiB in 5.02 secs:
> 74.12 MiB/sec (1523475 packets)
> Encrypting in chunks of 256 bytes: done. 369.85 MiB in 5.01 secs:
> 73.88 MiB/sec (1514900 packets)
> Encrypting in chunks of 256 bytes: done. 371.07 MiB in 5.02 secs:
> 73.97 MiB/sec (1519914 packets)
> Encrypting in chunks of 256 bytes: done. 371.66 MiB in 5.02 secs:
> 74.09 MiB/sec (1522309 packets)
> Encrypting in chunks of 256 bytes: done. 371.79 MiB in 5.02 secs:
> 74.12 MiB/sec (1522868 packets)
> Encrypting in chunks of 256 bytes: done. 371.94 MiB in 5.02 secs:
> 74.15 MiB/sec (1523457 packets)
> Encrypting in chunks of 256 bytes: done. 371.90 MiB in 5.02 secs:
> 74.14 MiB/sec (1523317 packets)
> Encrypting in chunks of 256 bytes: done. 371.71 MiB in 5.02 secs:
> 74.10 MiB/sec (1522522 packets)
>
> 15.95% qemu-kvm [.] address_space_translate
> 6.98% qemu-kvm [.] qemu_get_ram_ptr
> 4.87% libpthread-2.19.so [.] __pthread_mutex_unlock_usercnt
> 4.40% qemu-kvm [.] qemu_ram_addr_from_host
> 3.79% qemu-kvm [.] address_space_map
> 3.41% libc-2.19.so [.] _int_malloc
> 3.29% libc-2.19.so [.] _int_free
> 3.07% libc-2.19.so [.] malloc
> 2.95% libpthread-2.19.so [.] pthread_mutex_lock
> 2.94% qemu-kvm [.] phys_page_find
> 2.73% qemu-kvm [.] address_space_translate_internal
> 2.65% libc-2.19.so [.] malloc_consolidate
> 2.35% libc-2.19.so [.] __memcpy_sse2_unaligned
> 1.72% qemu-kvm [.] find_next_zero_bit
> 1.38% qemu-kvm [.] address_space_rw
> 1.34% qemu-kvm [.] object_unref
> 1.30% qemu-kvm [.] object_ref
> 1.28% qemu-kvm [.] virtqueue_pop
> 1.20% libc-2.19.so [.] memset
> 1.11% qemu-kvm [.] virtio_notify
>
> Thank you so much!
>
> Regards,
> -Gonglei
>
>> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
>> index 79a635f..2433866 100644
>> --- a/hw/virtio/virtio.c
>> +++ b/hw/virtio/virtio.c
>> @@ -107,35 +107,15 @@ void virtio_queue_update_rings(VirtIODevice *vdev,
>> int n)
>> vring->align);
>> }
>>
>> -static inline uint64_t vring_desc_addr(VirtIODevice *vdev, hwaddr desc_pa,
>> - int i)
>> +static void vring_desc_read(VirtIODevice *vdev, VRingDesc *desc,
>> + hwaddr desc_pa, int i)
>> {
>> - hwaddr pa;
>> - pa = desc_pa + sizeof(VRingDesc) * i + offsetof(VRingDesc, addr);
>> - return virtio_ldq_phys(vdev, pa);
>> -}
>> -
>> -static inline uint32_t vring_desc_len(VirtIODevice *vdev, hwaddr desc_pa,
>> int
>> i)
>> -{
>> - hwaddr pa;
>> - pa = desc_pa + sizeof(VRingDesc) * i + offsetof(VRingDesc, len);
>> - return virtio_ldl_phys(vdev, pa);
>> -}
>> -
>> -static inline uint16_t vring_desc_flags(VirtIODevice *vdev, hwaddr desc_pa,
>> - int i)
>> -{
>> - hwaddr pa;
>> - pa = desc_pa + sizeof(VRingDesc) * i + offsetof(VRingDesc, flags);
>> - return virtio_lduw_phys(vdev, pa);
>> -}
>> -
>> -static inline uint16_t vring_desc_next(VirtIODevice *vdev, hwaddr desc_pa,
>> - int i)
>> -{
>> - hwaddr pa;
>> - pa = desc_pa + sizeof(VRingDesc) * i + offsetof(VRingDesc, next);
>> - return virtio_lduw_phys(vdev, pa);
>> + address_space_read(&address_space_memory, desc_pa + i *
>> sizeof(VRingDesc),
>> + MEMTXATTRS_UNSPECIFIED, (void *)desc,
>> sizeof(VRingDesc));
>> + virtio_tswap64s(vdev, &desc->addr);
>> + virtio_tswap32s(vdev, &desc->len);
>> + virtio_tswap16s(vdev, &desc->flags);
>> + virtio_tswap16s(vdev, &desc->next);
>> }
>>
>> static inline uint16_t vring_avail_flags(VirtQueue *vq)
>> @@ -345,18 +325,18 @@ static unsigned int virtqueue_get_head(VirtQueue
>> *vq, unsigned int idx)
>> return head;
>> }
>>
>> -static unsigned virtqueue_next_desc(VirtIODevice *vdev, hwaddr desc_pa,
>> - unsigned int i, unsigned int max)
>> +static unsigned virtqueue_read_next_desc(VirtIODevice *vdev, VRingDesc
>> *desc,
>> + hwaddr desc_pa, unsigned
>> int max)
>> {
>> unsigned int next;
>>
>> /* If this descriptor says it doesn't chain, we're done. */
>> - if (!(vring_desc_flags(vdev, desc_pa, i) & VRING_DESC_F_NEXT)) {
>> + if (!(desc->flags & VRING_DESC_F_NEXT)) {
>> return max;
>> }
>>
>> /* Check they're not leading us off end of descriptors. */
>> - next = vring_desc_next(vdev, desc_pa, i);
>> + next = desc->next;
>> /* Make sure compiler knows to grab that: we don't want it changing! */
>> smp_wmb();
>>
>> @@ -365,6 +345,7 @@ static unsigned virtqueue_next_desc(VirtIODevice
>> *vdev, hwaddr desc_pa,
>> exit(1);
>> }
>>
>> + vring_desc_read(vdev, desc, desc_pa, next);
>> return next;
>> }
>>
>> @@ -381,6 +362,7 @@ void virtqueue_get_avail_bytes(VirtQueue *vq,
>> unsigned int *in_bytes,
>> while (virtqueue_num_heads(vq, idx)) {
>> VirtIODevice *vdev = vq->vdev;
>> unsigned int max, num_bufs, indirect = 0;
>> + VRingDesc desc;
>> hwaddr desc_pa;
>> int i;
>>
>> @@ -388,9 +370,10 @@ void virtqueue_get_avail_bytes(VirtQueue *vq,
>> unsigned int *in_bytes,
>> num_bufs = total_bufs;
>> i = virtqueue_get_head(vq, idx++);
>> desc_pa = vq->vring.desc;
>> + vring_desc_read(vdev, &desc, desc_pa, i);
>>
>> - if (vring_desc_flags(vdev, desc_pa, i) & VRING_DESC_F_INDIRECT) {
>> - if (vring_desc_len(vdev, desc_pa, i) % sizeof(VRingDesc)) {
>> + if (desc.flags & VRING_DESC_F_INDIRECT) {
>> + if (desc.len % sizeof(VRingDesc)) {
>> error_report("Invalid size for indirect buffer table");
>> exit(1);
>> }
>> @@ -403,9 +386,10 @@ void virtqueue_get_avail_bytes(VirtQueue *vq,
>> unsigned int *in_bytes,
>>
>> /* loop over the indirect descriptor table */
>> indirect = 1;
>> - max = vring_desc_len(vdev, desc_pa, i) / sizeof(VRingDesc);
>> - desc_pa = vring_desc_addr(vdev, desc_pa, i);
>> + max = desc.len / sizeof(VRingDesc);
>> + desc_pa = desc.addr;
>> num_bufs = i = 0;
>> + vring_desc_read(vdev, &desc, desc_pa, i);
>> }
>>
>> do {
>> @@ -415,15 +399,15 @@ void virtqueue_get_avail_bytes(VirtQueue *vq,
>> unsigned int *in_bytes,
>> exit(1);
>> }
>>
>> - if (vring_desc_flags(vdev, desc_pa, i) & VRING_DESC_F_WRITE)
>> {
>> - in_total += vring_desc_len(vdev, desc_pa, i);
>> + if (desc.flags & VRING_DESC_F_WRITE) {
>> + in_total += desc.len;
>> } else {
>> - out_total += vring_desc_len(vdev, desc_pa, i);
>> + out_total += desc.len;
>> }
>> if (in_total >= max_in_bytes && out_total >= max_out_bytes) {
>> goto done;
>> }
>> - } while ((i = virtqueue_next_desc(vdev, desc_pa, i, max)) != max);
>> + } while ((i = virtqueue_read_next_desc(vdev, &desc, desc_pa,
>> max)) != max);
>>
>> if (!indirect)
>> total_bufs = num_bufs;
>> @@ -545,6 +529,7 @@ void *virtqueue_pop(VirtQueue *vq, size_t sz)
>> unsigned out_num, in_num;
>> hwaddr addr[VIRTQUEUE_MAX_SIZE];
>> struct iovec iov[VIRTQUEUE_MAX_SIZE];
>> + VRingDesc desc;
>>
>> if (!virtqueue_num_heads(vq, vq->last_avail_idx)) {
>> return NULL;
>> @@ -560,33 +545,32 @@ void *virtqueue_pop(VirtQueue *vq, size_t sz)
>> vring_set_avail_event(vq, vq->last_avail_idx);
>> }
>>
>> - if (vring_desc_flags(vdev, desc_pa, i) & VRING_DESC_F_INDIRECT) {
>> - if (vring_desc_len(vdev, desc_pa, i) % sizeof(VRingDesc)) {
>> + vring_desc_read(vdev, &desc, desc_pa, i);
>> + if (desc.flags & VRING_DESC_F_INDIRECT) {
>> + if (desc.len % sizeof(VRingDesc)) {
>> error_report("Invalid size for indirect buffer table");
>> exit(1);
>> }
>>
>> /* loop over the indirect descriptor table */
>> - max = vring_desc_len(vdev, desc_pa, i) / sizeof(VRingDesc);
>> - desc_pa = vring_desc_addr(vdev, desc_pa, i);
>> + max = desc.len / sizeof(VRingDesc);
>> + desc_pa = desc.addr;
>> i = 0;
>> + vring_desc_read(vdev, &desc, desc_pa, i);
>> }
>>
>> /* Collect all the descriptors */
>> do {
>> - hwaddr pa = vring_desc_addr(vdev, desc_pa, i);
>> - size_t len = vring_desc_len(vdev, desc_pa, i);
>> -
>> - if (vring_desc_flags(vdev, desc_pa, i) & VRING_DESC_F_WRITE) {
>> + if (desc.flags & VRING_DESC_F_WRITE) {
>> virtqueue_map_desc(&in_num, addr + out_num, iov +
>> out_num,
>> - VIRTQUEUE_MAX_SIZE - out_num, true,
>> pa, len);
>> + VIRTQUEUE_MAX_SIZE - out_num, true,
>> desc.addr, desc.len);
>> } else {
>> if (in_num) {
>> error_report("Incorrect order for descriptors");
>> exit(1);
>> }
>> virtqueue_map_desc(&out_num, addr, iov,
>> - VIRTQUEUE_MAX_SIZE, false, pa, len);
>> + VIRTQUEUE_MAX_SIZE, false,
>> desc.addr, desc.len);
>> }
>>
>> /* If we've got too many, that implies a descriptor loop. */
>> @@ -594,7 +578,7 @@ void *virtqueue_pop(VirtQueue *vq, size_t sz)
>> error_report("Looped descriptor");
>> exit(1);
>> }
>> - } while ((i = virtqueue_next_desc(vdev, desc_pa, i, max)) != max);
>> + } while ((i = virtqueue_read_next_desc(vdev, &desc, desc_pa, max)) !=
>> max);
>>
>> /* Now copy what we have collected and mapped */
>> elem = virtqueue_alloc_element(sz, out_num, in_num);
>> --
>> 2.5.0
>>
>>
>
>
>
