netdev - Re: [PATCH net-next] tcp: forbid direct reclaim if MSG

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Message-ID: <CANn89i+-g5DEnrv0DSCsMq3fXo35mAaOmXvf1Tr22Ybif1OV0Q@mail.gmail.com>
Date:   Tue, 9 Oct 2018 08:38:39 -0700
From:   Eric Dumazet <edumazet@...gle.com>
To:     Yafang Shao <laoar.shao@...il.com>
Cc:     David Miller <davem@...emloft.net>,
        netdev <netdev@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net-next] tcp: forbid direct reclaim if MSG_DONTWAIT is
 set in send path

On Tue, Oct 9, 2018 at 7:58 AM Eric Dumazet <edumazet@...gle.com> wrote:
>

> We do not add bloat in the kernel if no application is ever going to
> use it, especially in the TCP fast path.
>

BTW, are you willing to change all memory allocations in the kernel as well ?

Let say an application is using a system call providing a pathname
(open(), stat(), ...), how this system call
is going to ask the kernel for no direct reclaim ?

Even allocating a socket with socket() or accept() has no ability to
avoid direct reclaim.

So tcp_sendmsg() is only the tip of the iceberg.