Subject: Re: [PATCH v4 2/5] LoongArch: Use la.pcrel instead of la.abs for
 exception handlers
To:     Huacai Chen <chenhuacai@kernel.org>, Xi Ruoyao <xry111@xry111.site>
References: <1676018856-26520-1-git-send-email-tangyouling@loongson.cn>
 <1676018856-26520-3-git-send-email-tangyouling@loongson.cn>
 <CAAhV-H4Bs5n_ek3mq6zwxAgVw0nvER1XUA+WUA8M12eKcYVPDQ@mail.gmail.com>
 <05ef2d91-ab87-b8d9-85fa-6a90a92f8f39@loongson.cn>
Cc:     Jinyang He <hejinyang@loongson.cn>,
        Xuerui Wang <kernel@xen0n.name>, loongarch@lists.linux.dev,
        linux-kernel@vger.kernel.org, Xuefeng Li <lixuefeng@loongson.cn>,
        Jianmin lv <lvjianmin@loongson.cn>,
        Tiezhu Yang <yangtiezhu@loongson.cn>
From:   Youling Tang <tangyouling@loongson.cn>
Message-ID: <848e2985-9ba3-c14d-23ac-a7f1c218215f@loongson.cn>
Date:   Thu, 16 Feb 2023 10:32:48 +0800
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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.