lkml.org 
[lkml]   [2021]   [Jun]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH 1/1] bpf: avoid unnecessary IPI in bpf_flush_icache
From
Date


On 6/3/21 1:26 AM, Will Deacon wrote:
> [Please note: This e-mail is from an EXTERNAL e-mail address]
>
> On Wed, Jun 02, 2021 at 07:26:03PM +0800, Xu, Yanfei wrote:
>>
>>
>> On 6/2/21 1:41 AM, Will Deacon wrote:
>>> [Please note: This e-mail is from an EXTERNAL e-mail address]
>>>
>>> On Tue, Jun 01, 2021 at 07:20:04PM +0200, Daniel Borkmann wrote:
>>>> On 6/1/21 5:06 PM, Yanfei Xu wrote:
>>>>> It's no need to trigger IPI for keeping pipeline fresh in bpf case.
>>>>
>>>> This needs a more concrete explanation/analysis on "why it is safe" to do so
>>>> rather than just saying that it is not needed.
>>>
>>> Agreed. You need to show how the executing thread ends up going through a
>>> context synchronizing operation before jumping to the generated code if
>>> the IPI here is removed.
>>
>> This patch came out with I looked through ftrace codes. Ftrace modify
>> the text code and don't send IPI in aarch64_insn_patch_text_nosync(). I
>> mistakenly thought the bpf is same with ftrace.
>>
>> But now I'm still not sure why the ftrace don't need the IPI to go
>> through context synchronizing, maybe the worst situation is omit a
>> tracing event?
>
> I think ftrace handles this itself via ftrace_sync_ipi, no?

Ah, Yes! I missed this...

Anyway, thanks for your reminding and very sorry for my noise.

Regards,
Yanfei

>
> Will
>

\
 
 \ /
  Last update: 2021-06-03 12:30    [W:0.092 / U:0.168 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site