From: Waiman Long <llong@redhat.com>
To: Xiongwei Song <sxwjean@me.com>, Waiman Long <llong@redhat.com>
Cc: peterz@infradead.org, mingo@redhat.com, will@kernel.org,
boqun.feng@gmail.com, linux-kernel@vger.kernel.org,
Xiongwei Song <sxwjean@gmail.com>
Subject: Re: [PATCH] locking/lockdep: unlikely bfs error check
Date: Wed, 16 Jun 2021 11:11:21 -0400 [thread overview]
Message-ID: <9c60a4a9-c241-73de-57b5-c5fc45720677@redhat.com> (raw)
In-Reply-To: <BF7CB29B-0B34-4462-B793-732C1EF9DC40@me.com>
On 6/16/21 10:59 AM, Xiongwei Song wrote:
>
>> On Jun 16, 2021, at 10:48 PM, Waiman Long <llong@redhat.com> wrote:
>>
>> On 6/16/21 10:42 AM, Xiongwei Song wrote:
>>> From: Xiongwei Song <sxwjean@gmail.com>
>>>
>>> The error from graph walk is small probability event, so unlikely
>>> bfs_error can improve performance a little bit.
>>>
>>> Signed-off-by: Xiongwei Song <sxwjean@gmail.com>
>>> ---
>>> kernel/locking/lockdep.c | 12 ++++++------
>>> 1 file changed, 6 insertions(+), 6 deletions(-)
>>>
>>> diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
>>> index 074fd6418c20..af8c9203cd3e 100644
>>> --- a/kernel/locking/lockdep.c
>>> +++ b/kernel/locking/lockdep.c
>>> @@ -2646,7 +2646,7 @@ static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
>>> bfs_init_rootb(&this, prev);
>>> ret = __bfs_backwards(&this, &usage_mask, usage_accumulate, usage_skip, NULL);
>>> - if (bfs_error(ret)) {
>>> + if (unlikely(bfs_error(ret))) {
>>> print_bfs_bug(ret);
>>> return 0;
>>> }
>>> @@ -2664,7 +2664,7 @@ static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
>>> bfs_init_root(&that, next);
>>> ret = find_usage_forwards(&that, forward_mask, &target_entry1);
>>> - if (bfs_error(ret)) {
>>> + if (unlikely(bfs_error(ret))) {
>>> print_bfs_bug(ret);
>>> return 0;
>>> }
>>> @@ -2679,7 +2679,7 @@ static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
>>> backward_mask = original_mask(target_entry1->class->usage_mask);
>>> ret = find_usage_backwards(&this, backward_mask, &target_entry);
>>> - if (bfs_error(ret)) {
>>> + if (unlikely(bfs_error(ret))) {
>>> print_bfs_bug(ret);
>>> return 0;
>>> }
>>> @@ -2998,7 +2998,7 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev,
>>> * Is the <prev> -> <next> link redundant?
>>> */
>>> ret = check_redundant(prev, next);
>>> - if (bfs_error(ret))
>>> + if (unlikely(bfs_error(ret)))
>>> return 0;
>>> else if (ret == BFS_RMATCH)
>>> return 2;
>>> @@ -3911,7 +3911,7 @@ check_usage_forwards(struct task_struct *curr, struct held_lock *this,
>>> bfs_init_root(&root, this);
>>> ret = find_usage_forwards(&root, usage_mask, &target_entry);
>>> - if (bfs_error(ret)) {
>>> + if (unlikely(bfs_error(ret))) {
>>> print_bfs_bug(ret);
>>> return 0;
>>> }
>>> @@ -3946,7 +3946,7 @@ check_usage_backwards(struct task_struct *curr, struct held_lock *this,
>>> bfs_init_rootb(&root, this);
>>> ret = find_usage_backwards(&root, usage_mask, &target_entry);
>>> - if (bfs_error(ret)) {
>>> + if (unlikely(bfs_error(ret))) {
>>> print_bfs_bug(ret);
>>> return 0;
>>> }
>> I think it is better to put the unlikely() directly into the bfs_error() inline function instead of sprinkling it all over the place.
> Sounds good. Thank you for the suggestion. I will update the patch.
Another nit. It is a bit odd that sent out two patches separately though
they do seem to have a bit of dependency. I think you should post them
as a 2-patch series.
Cheers,
Longman
next prev parent reply other threads:[~2021-06-16 15:11 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-16 14:42 [PATCH] locking/lockdep: unlikely bfs error check Xiongwei Song
2021-06-16 14:42 ` [PATCH] locking/lockdep: print possible warning after counting deps Xiongwei Song
2021-06-17 2:22 ` Xiongwei Song
2021-06-16 14:48 ` [PATCH] locking/lockdep: unlikely bfs error check Waiman Long
2021-06-16 14:59 ` Xiongwei Song
2021-06-16 15:11 ` Waiman Long [this message]
2021-06-17 2:14 ` Xiongwei Song
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=9c60a4a9-c241-73de-57b5-c5fc45720677@redhat.com \
--to=llong@redhat.com \
--cc=boqun.feng@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=peterz@infradead.org \
--cc=sxwjean@gmail.com \
--cc=sxwjean@me.com \
--cc=will@kernel.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).