lkml.org 
[lkml]   [2020]   [Dec]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH v2 bpf-next 10/13] bpf: Add instructions for atomic[64]_[fetch_]sub
On Tue, Dec 1, 2020 at 4:38 AM Brendan Jackman <jackmanb@google.com> wrote:
>
> I guess it's also worth remembering other archs might have an atomic
> subtract.

which one?
arm64 LSE implements atomic_fetch_sub as neg+ldadd.
imo x64 and arm64 example outweighs choices by other archs if there are such.
Even without LSE it will be neg+llsc loop.
The reason I proposed bpf xsub insn earlier is that I thought that llvm
won't be able to emit it so easily and JIT/verifier would struggle.

\
 
 \ /
  Last update: 2020-12-02 06:57    [W:0.072 / U:0.152 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site