From: Christoph Hellwig <hch@lst.de>
To: Sagi Grimberg <sagi@grimberg.me>
Cc: Keith Busch <kbusch@kernel.org>,
Mark Wunderlich <mark.wunderlich@intel.com>,
Anil Vasudevan <anil.vasudevan@intel.com>,
Christoph Hellwig <hch@lst.de>,
linux-nvme@lists.infradead.org
Subject: Re: [PATCH 1/2] nvme-tcp: set MSG_SENDPAGE_NOTLAST with MSG_MORE when we have more to send
Date: Tue, 5 May 2020 12:23:54 +0200 [thread overview]
Message-ID: <20200505102354.GB15038@lst.de> (raw)
In-Reply-To: <f0f28e18-c432-8343-f7a7-79cb3159b43c@grimberg.me>
On Mon, May 04, 2020 at 11:50:57PM -0700, Sagi Grimberg wrote:
>
>>> We can signal the stack that this is not the last page coming and the
>>> stack can build a larger tso segment, so go ahead and use it.
>>
>> Maybe you wan a little helper that returns the flags based on a last
>> flag? Something like:
>>
>> static int nvme_tcp_msg_flags(bool last_page)
>> {
>> if (last_page)
>> return MSG_DONTWAIT | MSG_MORE | MSG_SENDPAGE_NOTLAST;
>> return MSG_DONTWAIT | MSG_EOR;
>> }
>
> You have it reversed, the flag here probably means more...
>
> Let me see if it is useful to have, will let you know...
>
>>
>> or do we have a case where we don't want to set EOR? At least the
>> target seems to currently have such a case.
>
> As a design goal, we try to tell the stack explicitly if we have more
> to send and if not we want to push it down to reduce latency. So
> I think we need to have it in the target as well.
What I mean is that nvmet_try_send_data and nvmet_try_send_ddgst may set
neither MS_MORE nor MSG_EOR. Is that intentional?
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next prev parent reply other threads:[~2020-05-05 10:24 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-05 5:20 [PATCH 1/2] nvme-tcp: set MSG_SENDPAGE_NOTLAST with MSG_MORE when we have more to send Sagi Grimberg
2020-05-05 5:20 ` [PATCH 2/2] nvmet-tcp: " Sagi Grimberg
2020-05-12 16:13 ` Christoph Hellwig
2020-05-05 6:09 ` [PATCH 1/2] nvme-tcp: " Christoph Hellwig
2020-05-05 6:50 ` Sagi Grimberg
2020-05-05 10:23 ` Christoph Hellwig [this message]
2020-05-05 21:53 ` Sagi Grimberg
2020-05-06 4:27 ` Christoph Hellwig
2020-05-08 0:50 ` Sagi Grimberg
2020-05-08 7:35 ` Christoph Hellwig
2020-05-08 7:38 ` Sagi Grimberg
2020-05-12 16:12 ` Christoph Hellwig
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