From: Wei Yang <richard.weiyang@linux.alibaba.com>
To: rostedt@goodmis.org, mingo@redhat.com
Cc: linux-kernel@vger.kernel.org,
Wei Yang <richard.weiyang@linux.alibaba.com>
Subject: [PATCH 4/6] ftrace: simplify the calculation of page number for ftrace_page->records
Date: Mon, 31 Aug 2020 11:11:02 +0800 [thread overview]
Message-ID: <20200831031104.23322-5-richard.weiyang@linux.alibaba.com> (raw)
In-Reply-To: <20200831031104.23322-1-richard.weiyang@linux.alibaba.com>
Based on the following two reasones, we could simplify the calculation:
- If the number after roundup count is not power of 2, we would
definitely have more than 1 empty page with a higher order.
- get_count_order() just return current order, so one lower order
could meet the requirement.
The calculation could be simplified by lower one order level when pages
are not power of 2.
Signed-off-by: Wei Yang <richard.weiyang@linux.alibaba.com>
---
kernel/trace/ftrace.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 9021e16fa079..15fcfa16895d 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -3127,18 +3127,19 @@ static int ftrace_update_code(struct module *mod, struct ftrace_page *new_pgs)
static int ftrace_allocate_records(struct ftrace_page *pg, int count)
{
int order;
- int cnt;
+ int pages, cnt;
if (WARN_ON(!count))
return -EINVAL;
- order = get_count_order(DIV_ROUND_UP(count, ENTRIES_PER_PAGE));
+ pages = DIV_ROUND_UP(count, ENTRIES_PER_PAGE);
+ order = get_count_order(pages);
/*
* We want to fill as much as possible. No more than a page
* may be empty.
*/
- while ((PAGE_SIZE << order) / ENTRY_SIZE >= count + ENTRIES_PER_PAGE)
+ if (!is_power_of_2(pages))
order--;
again:
--
2.20.1 (Apple Git-117)
next prev parent reply other threads:[~2020-08-31 3:11 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-31 3:10 [PATCH 0/6] ftrace: trivial cleanup Wei Yang
2020-08-31 3:10 ` [PATCH 1/6] ftrace: define seq_file only for FMODE_READ Wei Yang
2020-10-06 14:36 ` Steven Rostedt
2020-10-08 3:34 ` Wei Yang
2020-08-31 3:11 ` [PATCH 2/6] ftrace: use fls() to get the bits for dup_hash() Wei Yang
2020-08-31 3:11 ` [PATCH 3/6] ftrace: simplify the dyn_ftrace->flags macro Wei Yang
2020-08-31 3:11 ` Wei Yang [this message]
2020-08-31 3:11 ` [PATCH 5/6] ftrace: replace do_for_each_ftrace_rec() with for_ftrace_rec_iter() Wei Yang
2020-10-06 14:42 ` Steven Rostedt
2020-10-08 3:34 ` Wei Yang
2020-08-31 3:11 ` [PATCH 6/6] ftrace: ftrace_global_list is renamed to ftrace_ops_list Wei Yang
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