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From: Carlos Llamas <cmllamas@google.com>
To: Waiman Long <longman@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	linux-kernel@vger.kernel.org, kernel-team@android.com,
	Peter Zijlstra <peterz@infradead.org>,
	Boqun Feng <boqun.feng@gmail.com>, Ingo Molnar <mingo@redhat.com>,
	Will Deacon <will@kernel.org>
Subject: Re: [PATCH 2/3] lockdep: clarify size for LOCKDEP_*_BITS configs
Date: Tue, 6 Aug 2024 14:47:52 +0000	[thread overview]
Message-ID: <ZrI3mFLUwDyEMRIB@google.com> (raw)
In-Reply-To: <218314e9-7c7c-490c-bb2e-9611243cade3@redhat.com>

On Mon, Aug 05, 2024 at 09:36:43PM -0400, Waiman Long wrote:
> 
> Many kernel developers understand that BITS refers to a size of 2^n. Besides
> LOCKDEP, there are also many instances of such use in other kconfig entries.
> It can be a bit odd to explicitly state that just for LOCKDEP.
> 
> Cheers,
> Longman

Right, and similar to BITS there is SHIFT, which is also a common way to
specify the 2^n values. I'd point out though, that it is also common to
clarify the "power of two" explicitly. To name a few examples that are
doing so: SECURITY_SELINUX_SIDTAB_HASH_BITS, NODES_SHIFT, CMA_ALIGNMENT,
IP_VS_SH_TAB_BITS, LOG_BUF_SHIFT but there is more.

Perhaps this is because the audience for these configs is not always a
kernel developer?

Anyway, this is pretty much a trivial patch to address Andrew's comment
below. But let me know if you think I should drop it, it seems to me it
can be helpful.

  [...]
  btw, the help text "Bitsize for MAX_LOCKDEP_CHAINS" is odd.  What's a
  bitsize?  Maybe "bit shift count for..." or such.

Thanks,
--
Carlos Llamas

  reply	other threads:[~2024-08-06 14:47 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-08-06  1:01 [PATCH 0/3] lockdep: minor config and documentation fixes Carlos Llamas
2024-08-06  1:01 ` [PATCH 1/3] lockdep: fix upper limit for LOCKDEP_*_BITS configs Carlos Llamas
2024-08-06  1:29   ` Waiman Long
2024-08-06  1:01 ` [PATCH 2/3] lockdep: clarify size " Carlos Llamas
2024-08-06  1:36   ` Waiman Long
2024-08-06 14:47     ` Carlos Llamas [this message]
2024-08-06 14:52       ` Waiman Long
2024-08-06 17:42         ` Boqun Feng
2024-08-07 14:28           ` Carlos Llamas
2024-08-06  1:01 ` [PATCH 3/3] lockdep: document MAX_LOCKDEP_CHAIN_HLOCKS calculation Carlos Llamas
2024-08-06  1:27   ` Waiman Long
2024-08-06 14:49     ` Carlos Llamas

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