lkml.org 
[lkml]   [2020]   [Jan]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH 0/2] optimise sqe-to-req flags
From
Date
On 1/17/20 3:41 PM, Pavel Begunkov wrote:
> *lost the cover-letter, but here we go*
>
> The main idea is to optimise code like the following by directly
> copying sqe flags:
>
> if (sqe_flags & IOSQE_IO_HARDLINK)
> req->flags |= REQ_F_HARDLINK;
>
> The first patch is a minor cleanup, and the second one do the
> trick. No functional changes.
>
> The other thing to consider is whether to use such flags as
> REQ_F_LINK = IOSQE_IO_LINK, or directly use IOSQE_IO_LINK instead.

I think we should keep the names separate. I think it looks fine, though
I do wish that we could just have both in an enum and not have to do
weird naming. We sometimes do:

enum {
__REQ_F_FOO
};

#define REQ_F_FOO (1U << __REQ_F_FOO)

and with that we could have things Just Work in terms of numbering, if
we keep the overlapped values at the start. Would need IOSQE_* to also
use an enum, ala:

enum {
__IOSQE_FIXED_FILE,
__IOSQE_IO_DRAIN,
...
};

and then do

#define IOSQE_FIXED_FILE (1U << __IOSQE_FIXED_FILE)

and have the __REQ enum start with

enum {
__REQ_F_FIXED_FILE = __IOSQE_FIXED_FILE,
__REQ_F_IO_DRAIN = __IOSQE_IO_DRAIN,
...
__REQ_F_LINK_NEXT,
__REQ_F_FAIL_LINK,
...
};

--
Jens Axboe

\
 
 \ /
  Last update: 2020-01-17 23:51    [W:0.070 / U:0.236 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site