Date: Tue, 29 Jul 2014 16:24:04 -0700 From: John-Mark Gurney <jmg@funkthat.com> To: Gleb Smirnoff <glebius@freebsd.org> Cc: arch@freebsd.org Subject: Re: [CFT/review] new sendfile(2) Message-ID: <20140729232404.GF43962@funkthat.com> In-Reply-To: <20140529102054.GX50679@FreeBSD.org> References: <20140529102054.GX50679@FreeBSD.org>
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Gleb Smirnoff wrote this message on Thu, May 29, 2014 at 14:20 +0400:
> One of the approaches we are experimenting with is new sendfile(2)
> implementation, that doesn't block on the I/O done from the file
> descriptor.
I know this is a reply to an old message, but...
How is this different from:
SF_NODISKIO. This flag causes any sendfile() call which would
block on disk I/O to instead return EBUSY. Busy servers may bene-
fit by transferring requests that would block to a separate I/O
worker thread.
> The patch for review is available at:
>
> https://phabric.freebsd.org/D102
Not public, so couldn't see the state...
> And for those who prefer email attachments, it is also attached.
> The patch has 3 logically separate changes in itself:
>
> 1) Split of socket buffer sb_cc field into sb_acc and sb_ccc. Where
> sb_acc stands for "available character count" and sb_ccc is "claimed
> character count". This allows us to write a data to a socket, that is
> not ready yet. The data sits in the socket, consumes its space, and
> keeps itself in the right order with earlier or later writes to socket.
> But it can be send only after it is marked as ready. This change is
> split across many files.
This change really should be split out and possibly committed seperately
after a review by the proper people...
> 2) A new vnode operation: VOP_GETPAGES_ASYNC(). This one lives in sys/vm.
>
> 3) Actual implementation of new sendfile(2). This one lives in
> kern/uipc_syscalls.c
--
John-Mark Gurney Voice: +1 415 225 5579
"All that I will do, has been done, All that I have, has not."
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