From: Qian Cai <cai@lca.pw>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: Mark Rutland <Mark.Rutland@arm.com>,
linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org,
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"David S. Miller" <davem@davemloft.net>
Subject: Re: [PATCH V12] mm/debug: Add tests validating architecture page table helpers
Date: Wed, 29 Jan 2020 06:09:56 -0500 [thread overview]
Message-ID: <50B7EFFE-1FF0-4B16-84A1-D851052B18B4@lca.pw> (raw)
In-Reply-To: <20200129103640.GA668562@arrakis.emea.arm.com>
> On Jan 29, 2020, at 5:36 AM, Catalin Marinas <catalin.marinas@arm.com> wrote:
>
> On Tue, Jan 28, 2020 at 02:07:10PM -0500, Qian Cai wrote:
>> On Jan 28, 2020, at 12:47 PM, Catalin Marinas <catalin.marinas@arm.com> wrote:
>>> The primary goal here is not finding regressions but having clearly
>>> defined semantics of the page table accessors across architectures. x86
>>> and arm64 are a good starting point and other architectures will be
>>> enabled as they are aligned to the same semantics.
>>
>> This still does not answer the fundamental question. If this test is
>> simply inefficient to find bugs,
>
> Who said this is inefficient (other than you)?
Inefficient of finding bugs. It said only found a bug or two in its lifetime?
>
>> who wants to spend time to use it regularly?
>
> Arch maintainers, mm maintainers introducing new macros or assuming
> certain new semantics of the existing macros.
>
>> If this is just one off test that may get running once in a few years
>> (when introducing a new arch), how does it justify the ongoing cost to
>> maintain it?
>
> You are really missing the point. It's not only for a new arch but
> changes to existing arch code. And if the arch code churn in this area
> is relatively small, I'd expect a similarly small cost of maintaining
> this test.
>
> If you only turn DEBUG_VM on once every few years, don't generalise this
> to the rest of the kernel developers (as others pointed out, this test
> is default y if DEBUG_VM).
Quite the opposite, I am running DEBUG_VM almost daily for regression
workload while I felt strongly this thing does not add any value mixing there.
So, I would suggest to decouple this away from DEBUG_VM, and clearly
document that this test is not something intended for automated regression
workloads, so those people don’t need to waste time running this.
>
> Anyway, I think that's a pointless discussion, so not going to reply
> further (unless you have technical content to add).
>
> --
> Catalin
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next prev parent reply other threads:[~2020-01-29 11:10 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-28 1:27 [PATCH V12] mm/debug: Add tests validating architecture page table helpers Anshuman Khandual
2020-01-28 2:11 ` Qian Cai
2020-01-28 3:06 ` Anshuman Khandual
2020-01-28 3:33 ` Qian Cai
2020-01-28 4:57 ` Anshuman Khandual
2020-01-28 5:48 ` Qian Cai
2020-01-28 6:17 ` Christophe Leroy
2020-01-28 6:36 ` Qian Cai
2020-01-28 7:03 ` Anshuman Khandual
2020-01-28 7:07 ` Qian Cai
2020-01-28 6:13 ` Christophe Leroy
2020-01-28 7:12 ` Qian Cai
2020-01-28 11:58 ` Mark Brown
2020-01-28 12:09 ` Mike Rapoport
2020-01-28 17:14 ` Vineet Gupta
2020-01-29 22:20 ` Gerald Schaefer
2020-01-30 7:27 ` Mike Rapoport
2020-01-30 13:32 ` Anshuman Khandual
2020-01-28 17:47 ` Catalin Marinas
2020-01-28 19:07 ` Qian Cai
2020-01-29 10:36 ` Catalin Marinas
2020-01-29 11:09 ` Qian Cai [this message]
2020-01-28 17:05 ` Christophe Leroy
2020-01-30 13:04 ` Anshuman Khandual
2020-01-30 14:13 ` Christophe Leroy
2020-02-02 7:18 ` Anshuman Khandual
2020-02-02 8:31 ` Christophe Leroy
2020-02-02 11:26 ` Qian Cai
2020-02-03 15:14 ` Christophe Leroy
2020-02-03 15:48 ` Qian Cai
2020-02-02 8:26 ` Anshuman Khandual
2020-01-29 22:20 ` Gerald Schaefer
2020-01-30 13:11 ` Anshuman Khandual
2020-01-30 15:06 ` Anshuman Khandual
2020-02-10 15:37 ` Catalin Marinas
2020-02-12 9:42 ` Anshuman Khandual
2020-02-12 17:55 ` Gerald Schaefer
2020-02-13 2:15 ` Anshuman Khandual
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