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Message-ID: <2e06387d-036b-dde2-5ddc-734c65a2f50d@sberdevices.ru>
Date:   Thu, 23 Mar 2023 13:01:40 +0300
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Subject: Re: [RFC PATCH v5 0/2] allocate multiple skbuffs on tx
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To:     Stefan Hajnoczi <stefanha@redhat.com>,
        Stefano Garzarella <sgarzare@redhat.com>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Bobby Eshleman <bobby.eshleman@bytedance.com>
CC:     <kvm@vger.kernel.org>, <virtualization@lists.linux-foundation.org>,
        <netdev@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <kernel@sberdevices.ru>, <oxffffaa@gmail.com>
References: <f0b283a1-cc63-dc3d-cc0c-0da7f684d4d2@sberdevices.ru>
From:   Arseniy Krasnov <avkrasnov@sberdevices.ru>
In-Reply-To: <f0b283a1-cc63-dc3d-cc0c-0da7f684d4d2@sberdevices.ru>
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Hello Stefano,

thanks for review!

Since both patches are R-b, i can wait for a few days, then send this
as 'net-next'?

Thanks, Arseniy

On 22.03.2023 21:34, 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.
> 
> Also this patchset includes second patch which adds check and return from
> 'virtio_transport_get_credit()' and 'virtio_transport_put_credit()' when
> these functions are called with 0 argument. This is needed, because zero
> argument makes both functions to behave as no-effect, but both of them
> always tries to acquire spinlock. Moreover, first patch always calls
> function 'virtio_transport_put_credit()' with zero argument in case of
> successful packet transmission.
> 
>  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/
>  Link to v4:
>  https://lore.kernel.org/netdev/0e0c1421-7cdc-2582-b120-cad6f42824bb@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.
> 
>  v4 -> v5:
>  - Remove extra 'ret' initialization.
>  - Remove empty extra line before 'if (ret < 0)'.
>  - Add R-b tag for the first patch.
>  - Add second patch, thus creating patchset of 2 patches.
> 
> Arseniy Krasnov (2):
>   virtio/vsock: allocate multiple skbuffs on tx
>   virtio/vsock: check argument to avoid no effect call
> 
>  net/vmw_vsock/virtio_transport_common.c | 63 +++++++++++++++++++------
>  1 file changed, 49 insertions(+), 14 deletions(-)
>