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[PATCH v3 3/3] lockdep: document MAX_LOCKDEP_CHAIN_HLOCKS calculation

Carlos Llamas posted 3 patches 1 year, 3 months ago
[PATCH v3 3/3] lockdep: document MAX_LOCKDEP_CHAIN_HLOCKS calculation
Posted by Carlos Llamas 1 year, 3 months ago 
Define a macro AVG_LOCKDEP_CHAIN_DEPTH to document the magic number '5'
used in the calculation of MAX_LOCKDEP_CHAIN_HLOCKS. The number
represents the estimated average depth (number of locks held) of a lock
chain. The calculation of MAX_LOCKDEP_CHAIN_HLOCKS was first added in
commit 443cd507ce7f ("lockdep: add lock_class information to lock_chain
and output it").

Suggested-by: Waiman Long <longman@redhat.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: J. R. Okajima <hooanon05g@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Will Deacon <will@kernel.org>
Acked-by: Waiman Long <longman@redhat.com>
Signed-off-by: Carlos Llamas <cmllamas@google.com>
---
v3: collect tags
v2: switched the comment for a macro as suggested by Waiman Long.

 kernel/locking/lockdep_internals.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/locking/lockdep_internals.h b/kernel/locking/lockdep_internals.h
index bbe9000260d0..20f9ef58d3d0 100644
--- a/kernel/locking/lockdep_internals.h
+++ b/kernel/locking/lockdep_internals.h
@@ -119,7 +119,8 @@ static const unsigned long LOCKF_USED_IN_IRQ_READ =
 
 #define MAX_LOCKDEP_CHAINS	(1UL << MAX_LOCKDEP_CHAINS_BITS)
 
-#define MAX_LOCKDEP_CHAIN_HLOCKS (MAX_LOCKDEP_CHAINS*5)
+#define AVG_LOCKDEP_CHAIN_DEPTH		5
+#define MAX_LOCKDEP_CHAIN_HLOCKS (MAX_LOCKDEP_CHAINS * AVG_LOCKDEP_CHAIN_DEPTH)
 
 extern struct lock_chain lock_chains[];
 
-- 
2.47.0.163.g1226f6d8fa-goog
Re: [PATCH v3 3/3] lockdep: document MAX_LOCKDEP_CHAIN_HLOCKS calculation
Posted by Huang, Ying 1 year, 3 months ago 
Carlos Llamas <cmllamas@google.com> writes:

> Define a macro AVG_LOCKDEP_CHAIN_DEPTH to document the magic number '5'
> used in the calculation of MAX_LOCKDEP_CHAIN_HLOCKS. The number
> represents the estimated average depth (number of locks held) of a lock
> chain. The calculation of MAX_LOCKDEP_CHAIN_HLOCKS was first added in
> commit 443cd507ce7f ("lockdep: add lock_class information to lock_chain
> and output it").
>
> Suggested-by: Waiman Long <longman@redhat.com>
> Cc: Huang Ying <ying.huang@intel.com>
> Cc: J. R. Okajima <hooanon05g@gmail.com>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Boqun Feng <boqun.feng@gmail.com>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: Will Deacon <will@kernel.org>
> Acked-by: Waiman Long <longman@redhat.com>
> Signed-off-by: Carlos Llamas <cmllamas@google.com>

LGTM, Thanks!  Feel free to add

Acked-by: "Huang, Ying" <ying.huang@intel.com>

in the future versions.

> ---
> v3: collect tags
> v2: switched the comment for a macro as suggested by Waiman Long.
>
>  kernel/locking/lockdep_internals.h | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/locking/lockdep_internals.h b/kernel/locking/lockdep_internals.h
> index bbe9000260d0..20f9ef58d3d0 100644
> --- a/kernel/locking/lockdep_internals.h
> +++ b/kernel/locking/lockdep_internals.h
> @@ -119,7 +119,8 @@ static const unsigned long LOCKF_USED_IN_IRQ_READ =
>  
>  #define MAX_LOCKDEP_CHAINS	(1UL << MAX_LOCKDEP_CHAINS_BITS)
>  
> -#define MAX_LOCKDEP_CHAIN_HLOCKS (MAX_LOCKDEP_CHAINS*5)
> +#define AVG_LOCKDEP_CHAIN_DEPTH		5
> +#define MAX_LOCKDEP_CHAIN_HLOCKS (MAX_LOCKDEP_CHAINS * AVG_LOCKDEP_CHAIN_DEPTH)
>  
>  extern struct lock_chain lock_chains[];
Re: [PATCH v3 3/3] lockdep: document MAX_LOCKDEP_CHAIN_HLOCKS calculation
Posted by Waiman Long 1 year, 3 months ago 
On 10/24/24 2:36 PM, Carlos Llamas wrote:
> Define a macro AVG_LOCKDEP_CHAIN_DEPTH to document the magic number '5'
> used in the calculation of MAX_LOCKDEP_CHAIN_HLOCKS. The number
> represents the estimated average depth (number of locks held) of a lock
> chain. The calculation of MAX_LOCKDEP_CHAIN_HLOCKS was first added in
> commit 443cd507ce7f ("lockdep: add lock_class information to lock_chain
> and output it").
>
> Suggested-by: Waiman Long <longman@redhat.com>
> Cc: Huang Ying <ying.huang@intel.com>
> Cc: J. R. Okajima <hooanon05g@gmail.com>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Boqun Feng <boqun.feng@gmail.com>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: Will Deacon <will@kernel.org>
> Acked-by: Waiman Long <longman@redhat.com>
> Signed-off-by: Carlos Llamas <cmllamas@google.com>
> ---
> v3: collect tags
> v2: switched the comment for a macro as suggested by Waiman Long.
>
>   kernel/locking/lockdep_internals.h | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/locking/lockdep_internals.h b/kernel/locking/lockdep_internals.h
> index bbe9000260d0..20f9ef58d3d0 100644
> --- a/kernel/locking/lockdep_internals.h
> +++ b/kernel/locking/lockdep_internals.h
> @@ -119,7 +119,8 @@ static const unsigned long LOCKF_USED_IN_IRQ_READ =
>   
>   #define MAX_LOCKDEP_CHAINS	(1UL << MAX_LOCKDEP_CHAINS_BITS)
>   
> -#define MAX_LOCKDEP_CHAIN_HLOCKS (MAX_LOCKDEP_CHAINS*5)
> +#define AVG_LOCKDEP_CHAIN_DEPTH		5
> +#define MAX_LOCKDEP_CHAIN_HLOCKS (MAX_LOCKDEP_CHAINS * AVG_LOCKDEP_CHAIN_DEPTH)
>   
>   extern struct lock_chain lock_chains[];
>   
Acked-by: Waiman Long <longman@redhat.com>
[tip: locking/core] lockdep: Document MAX_LOCKDEP_CHAIN_HLOCKS calculation
Posted by tip-bot2 for Carlos Llamas 1 year, 1 month ago 
The following commit has been merged into the locking/core branch of tip:

Commit-ID:     bd7b5ae26618ad2bd6f6264e2cb6c5815d323e75
Gitweb:        https://git.kernel.org/tip/bd7b5ae26618ad2bd6f6264e2cb6c5815d323e75
Author:        Carlos Llamas <cmllamas@google.com>
AuthorDate:    Thu, 24 Oct 2024 18:36:28 
Committer:     Boqun Feng <boqun.feng@gmail.com>
CommitterDate: Sun, 15 Dec 2024 11:49:35 -08:00

lockdep: Document MAX_LOCKDEP_CHAIN_HLOCKS calculation

Define a macro AVG_LOCKDEP_CHAIN_DEPTH to document the magic number '5'
used in the calculation of MAX_LOCKDEP_CHAIN_HLOCKS. The number
represents the estimated average depth (number of locks held) of a lock
chain. The calculation of MAX_LOCKDEP_CHAIN_HLOCKS was first added in
commit 443cd507ce7f ("lockdep: add lock_class information to lock_chain
and output it").

Suggested-by: Waiman Long <longman@redhat.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: J. R. Okajima <hooanon05g@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Will Deacon <will@kernel.org>
Acked-by: Waiman Long <longman@redhat.com>
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Acked-by: "Huang, Ying" <ying.huang@intel.com>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://lore.kernel.org/r/20241024183631.643450-4-cmllamas@google.com
---
 kernel/locking/lockdep_internals.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/locking/lockdep_internals.h b/kernel/locking/lockdep_internals.h
index bbe9000..20f9ef5 100644
--- a/kernel/locking/lockdep_internals.h
+++ b/kernel/locking/lockdep_internals.h
@@ -119,7 +119,8 @@ static const unsigned long LOCKF_USED_IN_IRQ_READ =
 
 #define MAX_LOCKDEP_CHAINS	(1UL << MAX_LOCKDEP_CHAINS_BITS)
 
-#define MAX_LOCKDEP_CHAIN_HLOCKS (MAX_LOCKDEP_CHAINS*5)
+#define AVG_LOCKDEP_CHAIN_DEPTH		5
+#define MAX_LOCKDEP_CHAIN_HLOCKS (MAX_LOCKDEP_CHAINS * AVG_LOCKDEP_CHAIN_DEPTH)
 
 extern struct lock_chain lock_chains[];

Patchew 2.1-devel-b67e4c2

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