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From: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org
Cc: Ingo Molnar <mingo@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Linus Torvalds <torvalds@linux-foundation.org>
Subject: [for-next][PATCH 4/4] ftrace: Simplify the calculation of page number for ftrace_page->records some more
Date: Sat, 03 Apr 2021 10:33:51 -0400	[thread overview]
Message-ID: <20210403143431.982491171@goodmis.org> (raw)
In-Reply-To: 20210403143347.409590683@goodmis.org

From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>

Commit b40c6eabfcd40 ("ftrace: Simplify the calculation of page number for
ftrace_page->records") simplified the calculation of the number of pages
needed for each page group without having any empty pages, but it can be
simplified even further.

Link: https://lore.kernel.org/lkml/CAHk-=wjt9b7kxQ2J=aDNKbR1QBMB3Hiqb_hYcZbKsxGRSEb+gQ@mail.gmail.com/

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 kernel/trace/ftrace.c | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index f7bef5a9ada9..057e962ca5ce 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -3156,15 +3156,9 @@ static int ftrace_allocate_records(struct ftrace_page *pg, int count)
 	if (WARN_ON(!count))
 		return -EINVAL;
 
+	/* We want to fill as much as possible, with no empty pages */
 	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.
-	 */
-	if (!is_power_of_2(pages))
-		order--;
+	order = fls(pages) - 1;
 
  again:
 	pg->records = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, order);
-- 
2.30.1



      parent reply	other threads:[~2021-04-03 14:34 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-03 14:33 [for-next][PATCH 0/4] tracing: More updates for 5.13 Steven Rostedt
2021-04-03 14:33 ` [for-next][PATCH 1/4] tracing: Remove duplicate struct declaration in trace_events.h Steven Rostedt
2021-04-03 14:33 ` [for-next][PATCH 2/4] tracing: Remove unused argument from "ring_buffer_time_stamp() Steven Rostedt
2021-04-03 14:33 ` [for-next][PATCH 3/4] ftrace: Store the order of pages allocated in ftrace_page Steven Rostedt
2021-04-03 14:33 ` Steven Rostedt [this message]

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