From: Peter Zijlstra <peterz@infradead.org>
To: Nicholas Piggin <npiggin@gmail.com>
Cc: Huacai Chen <chenhuacai@loongson.cn>,
David Airlie <airlied@linux.ie>,
Andrew Morton <akpm@linux-foundation.org>,
Arnd Bergmann <arnd@arndb.de>, Huacai Chen <chenhuacai@gmail.com>,
Jiaxun Yang <jiaxun.yang@flygoat.com>,
linux-arch@vger.kernel.org, Xuefeng Li <lixuefeng@loongson.cn>,
Andy Lutomirski <luto@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH 06/19] LoongArch: Add exception/interrupt handling
Date: Tue, 27 Jul 2021 16:10:07 +0200 [thread overview]
Message-ID: <YQATv/MahhrKUu8Z@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <1625665981.7hbs7yesxx.astroid@bobo.none>
On Wed, Jul 07, 2021 at 11:56:37PM +1000, Nicholas Piggin wrote:
> Excerpts from Peter Zijlstra's message of July 6, 2021 9:06 pm:
> > On Tue, Jul 06, 2021 at 12:18:07PM +0800, Huacai Chen wrote:
> >> + .align 5 /* 32 byte rollback region */
> >> +SYM_FUNC_START(__arch_cpu_idle)
> >> + /* start of rollback region */
> >> + LONG_L t0, tp, TI_FLAGS
> >> + nop
> >> + andi t0, t0, _TIF_NEED_RESCHED
> >> + bnez t0, 1f
> >> + nop
> >> + nop
> >> + nop
> >> + idle 0
> >> + /* end of rollback region */
> >> +1:
> >> + jirl zero, ra, 0
> >> +SYM_FUNC_END(__arch_cpu_idle)
> >
> >> +/*
> >> + * Common Vectored Interrupt
> >> + * Complete the register saves and invoke the do_vi() handler
> >> + */
> >> +SYM_FUNC_START(except_vec_vi_handler)
> >> + la t1, __arch_cpu_idle
> >> + LONG_L t0, sp, PT_EPC
> >> + /* 32 byte rollback region */
> >> + ori t0, t0, 0x1f
> >> + xori t0, t0, 0x1f
> >> + bne t0, t1, 1f
> >> + LONG_S t0, sp, PT_EPC
> >
> > Seriously, you're having your interrupt handler recover from the idle
> > race? On a *new* architecture?
>
> It's heavily derived from MIPS (does that make the wholesale replacement
> of arch/mips copyright headers a bit questionable?).
>
> I don't think it's such a bad trick though -- restartable sequences
> before they were cool. It can let you save an irq disable in some
> cases (depending on the arch of course).
In this case you're making *every* interrupt slower. Simply adding a new
idle instruction, one that can be called with interrupts disabled and
will terminate on a pending interrupt, would've solved the issues much
nicer and reclaimed the cycles spend on this restart trick.
next prev parent reply other threads:[~2021-07-27 14:13 UTC|newest]
Thread overview: 131+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-06 4:18 [PATCH 00/19] arch: Add basic LoongArch support Huacai Chen
2021-07-06 4:18 ` [PATCH 01/19] LoongArch: Add elf-related definitions Huacai Chen
2021-07-06 4:18 ` [PATCH 02/19] LoongArch: Add writecombine support for drm Huacai Chen
2021-07-06 4:18 ` [PATCH 03/19] LoongArch: Add build infrastructure Huacai Chen
2021-07-06 10:12 ` Arnd Bergmann
2021-07-19 1:26 ` Huacai Chen
2021-07-19 7:43 ` Arnd Bergmann
2021-07-19 13:02 ` Huacai Chen
2021-07-06 10:35 ` Arnd Bergmann
2021-07-07 0:00 ` Randy Dunlap
2021-07-19 1:28 ` Huacai Chen
2021-07-06 4:18 ` [PATCH 05/19] LoongArch: Add boot and setup routines Huacai Chen
2021-07-06 10:16 ` Arnd Bergmann
2021-07-27 11:53 ` Huacai Chen
2021-07-27 12:40 ` Arnd Bergmann
2021-07-27 12:51 ` Ard Biesheuvel
2021-07-27 13:14 ` Arnd Bergmann
2021-07-27 16:22 ` Ard Biesheuvel
2021-07-27 17:53 ` Arnd Bergmann
2021-07-28 10:24 ` Huacai Chen
2021-07-06 10:55 ` Arnd Bergmann
2021-07-06 4:18 ` [PATCH 06/19] LoongArch: Add exception/interrupt handling Huacai Chen
2021-07-06 10:16 ` Arnd Bergmann
2021-07-06 10:56 ` Arnd Bergmann
2021-07-06 11:06 ` Peter Zijlstra
2021-07-07 13:56 ` Nicholas Piggin
2021-07-27 14:10 ` Peter Zijlstra [this message]
2021-07-27 15:08 ` Arnd Bergmann
2021-07-28 10:16 ` Huacai Chen
2021-07-28 12:23 ` Arnd Bergmann
2021-07-06 4:18 ` [PATCH 07/19] LoongArch: Add process management Huacai Chen
2021-07-06 10:16 ` Arnd Bergmann
2021-07-06 10:57 ` Arnd Bergmann
2021-07-06 11:09 ` Peter Zijlstra
2021-08-12 11:17 ` Huacai Chen
2021-08-12 12:29 ` Arnd Bergmann
2021-08-12 12:51 ` Huacai Chen
2021-07-06 4:18 ` [PATCH 08/19] LoongArch: Add memory management Huacai Chen
2021-07-06 10:16 ` Arnd Bergmann
2021-07-06 10:57 ` Arnd Bergmann
2021-08-12 11:20 ` Huacai Chen
2021-08-16 1:57 ` Guo Ren
2021-08-16 3:31 ` Huacai Chen
2021-07-06 4:18 ` [PATCH 09/19] LoongArch: Add system call support Huacai Chen
2021-07-06 10:17 ` Arnd Bergmann
2021-07-06 10:58 ` Arnd Bergmann
2021-07-07 4:24 ` Huacai Chen
2021-07-07 6:44 ` Arnd Bergmann
2021-07-07 7:00 ` Huacai Chen
2021-07-09 8:44 ` Huacai Chen
2021-07-06 13:51 ` Thomas Gleixner
2021-07-07 4:27 ` Huacai Chen
2021-08-12 12:40 ` Huacai Chen
2021-07-06 4:18 ` [PATCH 10/19] LoongArch: Add signal handling support Huacai Chen
2021-07-06 10:17 ` Arnd Bergmann
2021-07-06 10:59 ` Arnd Bergmann
2021-07-08 13:04 ` Huacai Chen
2021-07-08 13:23 ` Arnd Bergmann
2021-07-09 9:24 ` Huacai Chen
2021-07-09 10:22 ` Arnd Bergmann
2021-07-09 14:49 ` Eric W. Biederman
2021-07-09 15:59 ` Arnd Bergmann
2021-08-26 16:43 ` Xi Ruoyao
2021-08-27 4:23 ` Huacai Chen
2021-08-27 4:27 ` Xi Ruoyao
2021-07-06 4:18 ` [PATCH 11/19] LoongArch: Add elf and module support Huacai Chen
2021-07-06 4:18 ` [PATCH 12/19] LoongArch: Add misc common routines Huacai Chen
2021-07-06 10:17 ` Arnd Bergmann
2021-07-06 11:00 ` Arnd Bergmann
2021-07-23 10:41 ` Huacai Chen
2021-07-23 11:43 ` Arnd Bergmann
2021-07-24 12:53 ` Huacai Chen
2021-07-06 4:18 ` [PATCH 13/19] LoongArch: Add some library functions Huacai Chen
2021-07-06 10:17 ` Arnd Bergmann
2021-07-06 11:00 ` Arnd Bergmann
2021-08-12 11:22 ` Huacai Chen
2021-07-06 4:18 ` [PATCH 14/19] LoongArch: Add 64-bit Loongson platform Huacai Chen
2021-07-06 4:18 ` [PATCH 15/19] LoongArch: Add PCI controller support Huacai Chen
2021-07-06 10:17 ` Arnd Bergmann
2021-07-06 11:01 ` Arnd Bergmann
2021-08-12 11:29 ` Huacai Chen
2021-07-06 4:18 ` [PATCH 16/19] LoongArch: Add VDSO and VSYSCALL support Huacai Chen
2021-07-06 10:17 ` Arnd Bergmann
2021-07-06 11:02 ` Arnd Bergmann
2021-08-12 11:31 ` Huacai Chen
2021-07-06 4:18 ` [PATCH 17/19] LoongArch: Add multi-processor (SMP) support Huacai Chen
2021-07-06 10:17 ` Arnd Bergmann
2021-07-06 11:03 ` Arnd Bergmann
2021-07-06 11:32 ` Peter Zijlstra
2021-08-12 11:39 ` Huacai Chen
2021-07-06 11:56 ` Peter Zijlstra
2021-07-06 13:48 ` Peter Zijlstra
2021-08-12 11:41 ` Huacai Chen
2021-07-06 13:52 ` Peter Zijlstra
2021-07-06 4:18 ` [PATCH 18/19] LoongArch: Add Non-Uniform Memory Access (NUMA) support Huacai Chen
2021-07-06 10:18 ` Arnd Bergmann
2021-07-06 11:03 ` Arnd Bergmann
2021-08-12 11:46 ` Huacai Chen
2021-08-12 12:48 ` Arnd Bergmann
2021-07-06 4:18 ` [PATCH 19/19] LoongArch: Add Loongson-3 default config file Huacai Chen
2021-07-06 10:18 ` Arnd Bergmann
2021-07-06 11:04 ` Arnd Bergmann
2021-08-12 11:58 ` Huacai Chen
2021-08-12 12:50 ` Arnd Bergmann
2021-07-06 10:11 ` [PATCH 00/19] arch: Add basic LoongArch support Arnd Bergmann
2021-07-07 3:04 ` Huacai Chen
2021-07-07 7:28 ` Arnd Bergmann
2021-07-29 16:48 ` Huacai Chen
2021-07-30 20:50 ` Arnd Bergmann
2021-07-06 10:33 ` Arnd Bergmann
[not found] ` <20210706041820.1536502-5-chenhuacai@loongson.cn>
2021-07-06 10:16 ` [PATCH 04/19] LoongArch: Add common headers Arnd Bergmann
2021-08-12 11:05 ` Huacai Chen
2021-08-12 12:45 ` Arnd Bergmann
2021-08-13 3:30 ` Huacai Chen
2021-08-13 7:05 ` Arnd Bergmann
2021-08-13 8:14 ` Huacai Chen
2021-08-13 9:08 ` Arnd Bergmann
2021-08-14 2:50 ` Huacai Chen
2021-08-15 8:56 ` Arnd Bergmann
2021-08-16 4:10 ` Huacai Chen
2021-08-18 9:38 ` Arnd Bergmann
2021-08-20 4:00 ` Huacai Chen
2021-08-20 7:55 ` Arnd Bergmann
2021-08-21 8:16 ` Huacai Chen
2021-07-06 10:54 ` Arnd Bergmann
2021-07-06 10:57 ` Peter Zijlstra
2021-07-06 11:23 ` Peter Zijlstra
2021-07-06 12:59 ` Arnd Bergmann
2021-07-06 13:20 ` Peter Zijlstra
2021-07-06 13:37 ` Peter Zijlstra
2021-07-06 11:59 ` Peter Zijlstra
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=YQATv/MahhrKUu8Z@hirez.programming.kicks-ass.net \
--to=peterz@infradead.org \
--cc=airlied@linux.ie \
--cc=akpm@linux-foundation.org \
--cc=arnd@arndb.de \
--cc=chenhuacai@gmail.com \
--cc=chenhuacai@loongson.cn \
--cc=jiaxun.yang@flygoat.com \
--cc=linux-arch@vger.kernel.org \
--cc=lixuefeng@loongson.cn \
--cc=luto@kernel.org \
--cc=npiggin@gmail.com \
--cc=tglx@linutronix.de \
--cc=torvalds@linux-foundation.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).