linux-kernel - Re: [PATCH v2 1/3] x86: Move DEBUG

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Date:   Mon, 29 Apr 2019 22:05:54 +0200
From:   Ingo Molnar <mingo@...nel.org>
To:     Atish Patra <atish.patra@....com>
Cc:     linux-kernel@...r.kernel.org, Albert Ou <aou@...s.berkeley.edu>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Anup Patel <anup@...infault.org>,
        Borislav Petkov <bp@...en8.de>,
        Changbin Du <changbin.du@...el.com>,
        Gary Guo <gary@...yguo.net>, "H. Peter Anvin" <hpa@...or.com>,
        Ingo Molnar <mingo@...hat.com>,
        Kees Cook <keescook@...omium.org>, linux-mm@...ck.org,
        linux-riscv@...ts.infradead.org,
        Luc Van Oostenryck <luc.vanoostenryck@...il.com>,
        Palmer Dabbelt <palmer@...ive.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Vlastimil Babka <vbabka@...e.cz>,
        "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@...nel.org>,
        Christoph Hellwig <hch@...radead.org>
Subject: Re: [PATCH v2 1/3] x86: Move DEBUG_TLBFLUSH option.


* Atish Patra <atish.patra@....com> wrote:

> CONFIG_DEBUG_TLBFLUSH was added in 'commit 3df3212f9722 ("x86/tlb: add
> tlb_flushall_shift knob into debugfs")' to support tlb_flushall_shift
> knob. The knob was removed in 'commit e9f4e0a9fe27 ("x86/mm: Rip out
> complicated, out-of-date, buggy TLB flushing")'.  However, the debug
> option was never removed from Kconfig. It was reused in commit
> '9824cf9753ec ("mm: vmstats: tlb flush counters")' but the commit text
> was never updated accordingly.

Please, when you mention several commits, put them into new lines to make 
it readable, i.e.:

  3df3212f9722 ("x86/tlb: add tlb_flushall_shift knob into debugfs")

etc.

> Update the Kconfig option description as per its current usage.
> 
> Take this opprtunity to make this kconfig option a common option as it
> touches the common vmstat code. Introduce another arch specific config
> HAVE_ARCH_DEBUG_TLBFLUSH that can be selected to enable this config.

"opprtunity"?

> +config HAVE_ARCH_DEBUG_TLBFLUSH
> +	bool
> +	depends on DEBUG_KERNEL
> +
> +config DEBUG_TLBFLUSH
> +	bool "Save tlb flush statstics to vmstat"
> +	depends on HAVE_ARCH_DEBUG_TLBFLUSH
> +	help
> +
> +	Add tlbflush statstics to vmstat. It is really helpful understand tlbflush
> +	performance and behavior. It should be enabled only for debugging purpose
> +	by individual architectures explicitly by selecting HAVE_ARCH_DEBUG_TLBFLUSH.

"statstics"??

Please put a spell checker into your workflow or read what you are 
writing ...

Thanks,

	Ingo