Message-ID: <edb15f83-ddf9-ae48-6d1e-6ef7802e6f50@linux.alibaba.com>
Date:   Tue, 16 Nov 2021 20:42:28 +0800
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Subject: Re: [PATCH v2 1/2] scripts: ftrace - move the sort-processing in
 ftrace_init to compile time
To:     Peter Zijlstra <peterz@infradead.org>
Cc:     rostedt@goodmis.org, mark-pk.tsai@mediatek.com, mingo@redhat.com,
        linux-kernel@vger.kernel.org
References: <20210911135043.16014-1-yinan@linux.alibaba.com>
 <20211116024942.60644-1-yinan@linux.alibaba.com>
 <20211116024942.60644-2-yinan@linux.alibaba.com>
 <20211116080730.GV174703@worktop.programming.kicks-ass.net>
From:   Yinan Liu <yinan@linux.alibaba.com>
In-Reply-To: <20211116080730.GV174703@worktop.programming.kicks-ass.net>
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在 2021/11/16 下午4:07, Peter Zijlstra 写道:

> /me hands a bucket of {} your way. 

--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -6406,8 +6406,10 @@ static int ftrace_process_locs(struct module *mod,
         if (!count)
                 return 0;

-       sort(start, count, sizeof(*start),
-            ftrace_cmp_ips, NULL);
+       if (mod) {
+               sort(start, count, sizeof(*start),
+                    ftrace_cmp_ips, NULL);
+       }

hi，peter

you mean like this? I hope I'm not mistaken.


 > Also, can't sorttable be ran on modules ?

The .ko file will be relocated after insmod or modprobe.
And the mcount redirection in .ko is based on ".text",
".init.text", ".ref.text", ".sched.text", ".spinlock.text",
".irqentry .text", ".softirqentry.text", ".kprobes.text", 
".cpuidle.text", ".text.unlikely". These sections‘ loading
position are not in definite order.

So sorting this part at compile time doesn't make much sense.


Best regards!
--Yinan liu