Re: [PATCH net-next] tcp: forbid direct reclaim if MSG_DONTWAIT is set in send path

On Tue, Oct 9, 2018 at 11:38 PM Eric Dumazet [off-list ref] wrote:

On Tue, Oct 9, 2018 at 7:58 AM Eric Dumazet [off-list ref] wrote:

quoted

quoted

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.

If we can really find a solution that is good enough to hanlde direct
reclaim in tcp_sendmsg,
we could also implement it in other syscalls.
Unexpected latency is hateful.

Thanks
Yafang