| Message ID | 0e0c1421-7cdc-2582-b120-cad6f42824bb@sberdevices.ru (mailing list archive) |
|---|---|
| State | RFC |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [RFC,v4] virtio/vsock: allocate multiple skbuffs on tx | expand |
On Tue, Mar 21, 2023 at 06:03:14PM +0300, Arseniy Krasnov wrote: >This adds small optimization for tx path: instead of allocating single >skbuff on every call to transport, allocate multiple skbuff's until >credit space allows, thus trying to send as much as possible data without >return to af_vsock.c. > >Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru> >--- > Link to v1: > https://lore.kernel.org/netdev/2c52aa26-8181-d37a-bccd-a86bd3cbc6e1@sberdevices.ru/ > Link to v2: > https://lore.kernel.org/netdev/ea5725eb-6cb5-cf15-2938-34e335a442fa@sberdevices.ru/ > Link to v3: > https://lore.kernel.org/netdev/f33ef593-982e-2b3f-0986-6d537a3aaf08@sberdevices.ru/ > > Changelog: > v1 -> v2: > - If sent something, return number of bytes sent (even in > case of error). Return error only if failed to sent first > skbuff. > > v2 -> v3: > - Handle case when transport callback returns unexpected value which > is not equal to 'skb->len'. Break loop. > - Don't check for zero value of 'rest_len' before calling > 'virtio_transport_put_credit()'. Decided to add this check directly > to 'virtio_transport_put_credit()' in separate patch. > > v3 -> v4: > - Use WARN_ONCE() to handle case when transport callback returns > unexpected value. > - Remove useless 'ret = -EFAULT;' assignment for case above. > > net/vmw_vsock/virtio_transport_common.c | 59 +++++++++++++++++++------ > 1 file changed, 45 insertions(+), 14 deletions(-) > >diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c >index 6564192e7f20..a300f25749ea 100644 >--- a/net/vmw_vsock/virtio_transport_common.c >+++ b/net/vmw_vsock/virtio_transport_common.c >@@ -196,7 +196,8 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk, > const struct virtio_transport *t_ops; > struct virtio_vsock_sock *vvs; > u32 pkt_len = info->pkt_len; >- struct sk_buff *skb; >+ u32 rest_len; >+ int ret; > > info->type = virtio_transport_get_type(sk_vsock(vsk)); > >@@ -216,10 +217,6 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk, > > vvs = vsk->trans; > >- /* we can send less than pkt_len bytes */ >- if (pkt_len > VIRTIO_VSOCK_MAX_PKT_BUF_SIZE) >- pkt_len = VIRTIO_VSOCK_MAX_PKT_BUF_SIZE; >- > /* virtio_transport_get_credit might return less than pkt_len credit */ > pkt_len = virtio_transport_get_credit(vvs, pkt_len); > >@@ -227,17 +224,51 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk, > if (pkt_len == 0 && info->op == VIRTIO_VSOCK_OP_RW) > return pkt_len; > >- skb = virtio_transport_alloc_skb(info, pkt_len, >- src_cid, src_port, >- dst_cid, dst_port); >- if (!skb) { >- virtio_transport_put_credit(vvs, pkt_len); >- return -ENOMEM; >- } >+ ret = 0; nit: this initialization seems superfluous since `ret` is overwritten later ... >+ rest_len = pkt_len; >+ >+ do { >+ struct sk_buff *skb; >+ size_t skb_len; >+ >+ skb_len = min_t(u32, VIRTIO_VSOCK_MAX_PKT_BUF_SIZE, rest_len); >+ >+ skb = virtio_transport_alloc_skb(info, skb_len, >+ src_cid, src_port, >+ dst_cid, dst_port); >+ if (!skb) { >+ ret = -ENOMEM; >+ break; >+ } > >- virtio_transport_inc_tx_pkt(vvs, skb); >+ virtio_transport_inc_tx_pkt(vvs, skb); > >- return t_ops->send_pkt(skb); >+ ret = t_ops->send_pkt(skb); ... here. >+ nit: we can remove this extra line >+ if (ret < 0) >+ break; >+ >+ /* Both virtio and vhost 'send_pkt()' returns 'skb_len', >+ * but for reliability use 'ret' instead of 'skb_len'. >+ * Also if partial send happens (e.g. 'ret' != 'skb_len') >+ * somehow, we break this loop, but account such returned >+ * value in 'virtio_transport_put_credit()'. >+ */ >+ rest_len -= ret; >+ >+ if (WARN_ONCE(ret != skb_len, >+ "'send_pkt()' returns %i, but %zu expected\n", >+ ret, skb_len)) >+ break; >+ } while (rest_len); >+ >+ virtio_transport_put_credit(vvs, rest_len); >+ >+ /* Return number of bytes, if any data has been sent. */ >+ if (rest_len != pkt_len) >+ ret = pkt_len - rest_len; >+ >+ return ret; > } > > static bool virtio_transport_inc_rx_pkt(struct virtio_vsock_sock *vvs, >-- 2.25.1 > The patch LGTM: Reviewed-by: Stefano Garzarella <sgarzare@redhat.com> Anyway, feel free to include in the same series or as separate patch also the changes to avoid useless lock in virtio_transport_put_credit() and virtio_transport_get_credit(). I would include it in this series, because before these changes, we used to call virtio_transport_put_credit() only in the error path, while now we always call it, even when rest_len is 0. Thanks, Stefano
On 22.03.2023 17:41, Stefano Garzarella wrote: > On Tue, Mar 21, 2023 at 06:03:14PM +0300, Arseniy Krasnov wrote: >> This adds small optimization for tx path: instead of allocating single >> skbuff on every call to transport, allocate multiple skbuff's until >> credit space allows, thus trying to send as much as possible data without >> return to af_vsock.c. >> >> Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru> >> --- >> Link to v1: >> https://lore.kernel.org/netdev/2c52aa26-8181-d37a-bccd-a86bd3cbc6e1@sberdevices.ru/ >> Link to v2: >> https://lore.kernel.org/netdev/ea5725eb-6cb5-cf15-2938-34e335a442fa@sberdevices.ru/ >> Link to v3: >> https://lore.kernel.org/netdev/f33ef593-982e-2b3f-0986-6d537a3aaf08@sberdevices.ru/ >> >> Changelog: >> v1 -> v2: >> - If sent something, return number of bytes sent (even in >> case of error). Return error only if failed to sent first >> skbuff. >> >> v2 -> v3: >> - Handle case when transport callback returns unexpected value which >> is not equal to 'skb->len'. Break loop. >> - Don't check for zero value of 'rest_len' before calling >> 'virtio_transport_put_credit()'. Decided to add this check directly >> to 'virtio_transport_put_credit()' in separate patch. >> >> v3 -> v4: >> - Use WARN_ONCE() to handle case when transport callback returns >> unexpected value. >> - Remove useless 'ret = -EFAULT;' assignment for case above. >> >> net/vmw_vsock/virtio_transport_common.c | 59 +++++++++++++++++++------ >> 1 file changed, 45 insertions(+), 14 deletions(-) >> >> diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c >> index 6564192e7f20..a300f25749ea 100644 >> --- a/net/vmw_vsock/virtio_transport_common.c >> +++ b/net/vmw_vsock/virtio_transport_common.c >> @@ -196,7 +196,8 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk, >> const struct virtio_transport *t_ops; >> struct virtio_vsock_sock *vvs; >> u32 pkt_len = info->pkt_len; >> - struct sk_buff *skb; >> + u32 rest_len; >> + int ret; >> >> info->type = virtio_transport_get_type(sk_vsock(vsk)); >> >> @@ -216,10 +217,6 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk, >> >> vvs = vsk->trans; >> >> - /* we can send less than pkt_len bytes */ >> - if (pkt_len > VIRTIO_VSOCK_MAX_PKT_BUF_SIZE) >> - pkt_len = VIRTIO_VSOCK_MAX_PKT_BUF_SIZE; >> - >> /* virtio_transport_get_credit might return less than pkt_len credit */ >> pkt_len = virtio_transport_get_credit(vvs, pkt_len); >> >> @@ -227,17 +224,51 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk, >> if (pkt_len == 0 && info->op == VIRTIO_VSOCK_OP_RW) >> return pkt_len; >> >> - skb = virtio_transport_alloc_skb(info, pkt_len, >> - src_cid, src_port, >> - dst_cid, dst_port); >> - if (!skb) { >> - virtio_transport_put_credit(vvs, pkt_len); >> - return -ENOMEM; >> - } >> + ret = 0; > > nit: this initialization seems superfluous since `ret` is > overwritten later ... > >> + rest_len = pkt_len; >> + >> + do { >> + struct sk_buff *skb; >> + size_t skb_len; >> + >> + skb_len = min_t(u32, VIRTIO_VSOCK_MAX_PKT_BUF_SIZE, rest_len); >> + >> + skb = virtio_transport_alloc_skb(info, skb_len, >> + src_cid, src_port, >> + dst_cid, dst_port); >> + if (!skb) { >> + ret = -ENOMEM; >> + break; >> + } >> >> - virtio_transport_inc_tx_pkt(vvs, skb); >> + virtio_transport_inc_tx_pkt(vvs, skb); >> >> - return t_ops->send_pkt(skb); >> + ret = t_ops->send_pkt(skb); > > ... here. > >> + > > nit: we can remove this extra line > >> + if (ret < 0) >> + break; >> + >> + /* Both virtio and vhost 'send_pkt()' returns 'skb_len', >> + * but for reliability use 'ret' instead of 'skb_len'. >> + * Also if partial send happens (e.g. 'ret' != 'skb_len') >> + * somehow, we break this loop, but account such returned >> + * value in 'virtio_transport_put_credit()'. >> + */ >> + rest_len -= ret; >> + >> + if (WARN_ONCE(ret != skb_len, >> + "'send_pkt()' returns %i, but %zu expected\n", >> + ret, skb_len)) >> + break; >> + } while (rest_len); >> + >> + virtio_transport_put_credit(vvs, rest_len); >> + >> + /* Return number of bytes, if any data has been sent. */ >> + if (rest_len != pkt_len) >> + ret = pkt_len - rest_len; >> + >> + return ret; >> } >> >> static bool virtio_transport_inc_rx_pkt(struct virtio_vsock_sock *vvs, >> -- 2.25.1 >> > > The patch LGTM: > > Reviewed-by: Stefano Garzarella <sgarzare@redhat.com> > > Anyway, feel free to include in the same series or as separate patch > also the changes to avoid useless lock in virtio_transport_put_credit() > and virtio_transport_get_credit(). > > I would include it in this series, because before these changes, we > used to call virtio_transport_put_credit() only in the error path, > while now we always call it, even when rest_len is 0. Thanks for review, done! https://lore.kernel.org/netdev/f0b283a1-cc63-dc3d-cc0c-0da7f684d4d2@sberdevices.ru/ Added it as second patch to the series Thanks, Arseniy > > Thanks, > Stefano >
diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c index 6564192e7f20..a300f25749ea 100644 --- a/net/vmw_vsock/virtio_transport_common.c +++ b/net/vmw_vsock/virtio_transport_common.c @@ -196,7 +196,8 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk, const struct virtio_transport *t_ops; struct virtio_vsock_sock *vvs; u32 pkt_len = info->pkt_len; - struct sk_buff *skb; + u32 rest_len; + int ret; info->type = virtio_transport_get_type(sk_vsock(vsk)); @@ -216,10 +217,6 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk, vvs = vsk->trans; - /* we can send less than pkt_len bytes */ - if (pkt_len > VIRTIO_VSOCK_MAX_PKT_BUF_SIZE) - pkt_len = VIRTIO_VSOCK_MAX_PKT_BUF_SIZE; - /* virtio_transport_get_credit might return less than pkt_len credit */ pkt_len = virtio_transport_get_credit(vvs, pkt_len); @@ -227,17 +224,51 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk, if (pkt_len == 0 && info->op == VIRTIO_VSOCK_OP_RW) return pkt_len; - skb = virtio_transport_alloc_skb(info, pkt_len, - src_cid, src_port, - dst_cid, dst_port); - if (!skb) { - virtio_transport_put_credit(vvs, pkt_len); - return -ENOMEM; - } + ret = 0; + rest_len = pkt_len; + + do { + struct sk_buff *skb; + size_t skb_len; + + skb_len = min_t(u32, VIRTIO_VSOCK_MAX_PKT_BUF_SIZE, rest_len); + + skb = virtio_transport_alloc_skb(info, skb_len, + src_cid, src_port, + dst_cid, dst_port); + if (!skb) { + ret = -ENOMEM; + break; + } - virtio_transport_inc_tx_pkt(vvs, skb); + virtio_transport_inc_tx_pkt(vvs, skb); - return t_ops->send_pkt(skb); + ret = t_ops->send_pkt(skb); + + if (ret < 0) + break; + + /* Both virtio and vhost 'send_pkt()' returns 'skb_len', + * but for reliability use 'ret' instead of 'skb_len'. + * Also if partial send happens (e.g. 'ret' != 'skb_len') + * somehow, we break this loop, but account such returned + * value in 'virtio_transport_put_credit()'. + */ + rest_len -= ret; + + if (WARN_ONCE(ret != skb_len, + "'send_pkt()' returns %i, but %zu expected\n", + ret, skb_len)) + break; + } while (rest_len); + + virtio_transport_put_credit(vvs, rest_len); + + /* Return number of bytes, if any data has been sent. */ + if (rest_len != pkt_len) + ret = pkt_len - rest_len; + + return ret; } static bool virtio_transport_inc_rx_pkt(struct virtio_vsock_sock *vvs,
This adds small optimization for tx path: instead of allocating single skbuff on every call to transport, allocate multiple skbuff's until credit space allows, thus trying to send as much as possible data without return to af_vsock.c. Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru> --- Link to v1: https://lore.kernel.org/netdev/2c52aa26-8181-d37a-bccd-a86bd3cbc6e1@sberdevices.ru/ Link to v2: https://lore.kernel.org/netdev/ea5725eb-6cb5-cf15-2938-34e335a442fa@sberdevices.ru/ Link to v3: https://lore.kernel.org/netdev/f33ef593-982e-2b3f-0986-6d537a3aaf08@sberdevices.ru/ Changelog: v1 -> v2: - If sent something, return number of bytes sent (even in case of error). Return error only if failed to sent first skbuff. v2 -> v3: - Handle case when transport callback returns unexpected value which is not equal to 'skb->len'. Break loop. - Don't check for zero value of 'rest_len' before calling 'virtio_transport_put_credit()'. Decided to add this check directly to 'virtio_transport_put_credit()' in separate patch. v3 -> v4: - Use WARN_ONCE() to handle case when transport callback returns unexpected value. - Remove useless 'ret = -EFAULT;' assignment for case above. net/vmw_vsock/virtio_transport_common.c | 59 +++++++++++++++++++------ 1 file changed, 45 insertions(+), 14 deletions(-)