Re: [PATCH v4 2/5] LoongArch: Use la.pcrel instead of la.abs for exception handlers

[Youling Tang]

Hi folks,

On 02/10/2023 05:18 PM, Youling Tang wrote:
> On 02/10/2023 05:09 PM, Huacai Chen wrote:
> > Hi, Youling and Ruoyao,
> >
> > Thank you very much for implementing the per-node exceptions. But I
> > want to know if the per-node solution is really worthy for a PIE
> > kernel. So, could you please test the performance? Maybe we can reduce
> > the complexity if we give up the per-node solution.

Tested on Loongson-3C5000L-LL machine, using CLFS7.3 system.

- nopernode:
  Based on the v1 patch method, and remove the else branch process in
  setup_tlb_handler().

- pernode: Based on the v4 patch method.

- pie: Enable RANDOMIZE_BASE (KASLR).

- nopie: Disable RANDOMIZE_BASE and RELOCATABLE.


The UnixBench test results are as follows:

- nopernode-nopie: 3938.7

- pernode-nopie: 4062.2

- nopernode-pie: 4009.7

- pernode-pie: 4028.7

In general, `pernode` is higher than `nopernode`, and `nopie` is higher
than `pie`. (except that nopernode-pie is higher than nopernode-nopie,
which is not as expected, which may be caused by the instability of the
machine).

Everyone is more inclined to use `pernode` or `nopernode` to implement
in the exception handling process?

Youling.