lkml.org 
[lkml]   [2020]   [Aug]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH 1/2 v3] rseq/membarrier: add MEMBARRIER_CMD_PRIVATE_EXPEDITED_RSEQ
On Tue, Aug 25, 2020 at 9:58 AM Mathieu Desnoyers
<mathieu.desnoyers@efficios.com> wrote:
>
[...]
>
> Concretely speaking, let's just add a new membarrier command for the use-case
> at hand. All other ways of doing things we have discussed are tricky to expose
> in a way that is discoverable by user-space through the QUERY command. (using
> a flag, or OR'ing many commands together)
>
> >
> > 2: should @flags be repurposed for cpu_id, or MEMBARRIER_FLAG_CPU
> > added with a new syscall parameter.
> > => I'm still not sure a new parameter can be cleanly added, but I can try
> > it in the next patchset if you prefer it this way.
>
> Yes please, it's easy to implement and we'll quickly see if anyone yells. If
> it turns out to be a bad idea, you can always blame me. ;-)
>
> In summary:
>
> - We add 2 new membarrier commands:
> - MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED_RSEQ
> - MEMBARRIER_CMD_PRIVATE_EXPEDITED_RSEQ
>
> - We reserve a membarrier flag:
>
> enum membarrier_flag {
> MEMBARRIER_FLAG_CPU = (1 << 0),
> }
>
> So for CMD_PRIVATE_EXPEDITED_RSEQ, if flags & MEMBARRIER_FLAG_CPU is true,
> then we expect the additional "int cpu" parameter (3rd parameter). Else the cpu
> parameter is unused.
>
> Are you OK with this approach ?

Yes, thanks for looking into this. I'll send a v4 later this week.

Thanks,
Peter

[...]

\
 
 \ /
  Last update: 2020-08-25 19:23    [W:0.211 / U:0.024 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site