Messages in this thread | | | Subject | Re: [PATCH 1/1] bpf: avoid unnecessary IPI in bpf_flush_icache | From | "Xu, Yanfei" <> | Date | Thu, 3 Jun 2021 18:29:16 +0800 |
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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 >
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