Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932722AbdC1NOp (ORCPT ); Tue, 28 Mar 2017 09:14:45 -0400 Received: from szxga03-in.huawei.com ([45.249.212.189]:4901 "EHLO dggrg03-dlp.huawei.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1751936AbdC1NOl (ORCPT ); Tue, 28 Mar 2017 09:14:41 -0400 From: Zhou Chengming To: , CC: , , , , , , Subject: [PATCH v2] livepatch: Reduce the time of finding module symbols Date: Tue, 28 Mar 2017 21:10:35 +0800 Message-ID: <1490706635-45752-1-git-send-email-zhouchengming1@huawei.com> X-Mailer: git-send-email 1.8.3.1 MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.175.113.25] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A020206.58DA617D.00A6,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0, ip=0.0.0.0, so=2014-11-16 11:51:01, dmn=2013-03-21 17:37:32 X-Mirapoint-Loop-Id: 51e545d6d5f24543fba1727e8546fb30 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1457 Lines: 46 It's reported that the time of insmoding a klp.ko for one of our out-tree modules is too long. ~ time sudo insmod klp.ko real 0m23.799s user 0m0.036s sys 0m21.256s Then we found the reason: our out-tree module used a lot of static local variables, so klp.ko has a lot of relocation records which reference the module. Then for each such entry klp_find_object_symbol() is called to resolve it, but this function uses the interface kallsyms_on_each_symbol() even for finding module symbols, so will waste a lot of time on walking through vmlinux kallsyms table many times. This patch changes it to use module_kallsyms_on_each_symbol() for modules symbols. After we apply this patch, the sys time reduced dramatically. ~ time sudo insmod klp.ko real 0m1.007s user 0m0.032s sys 0m0.924s Signed-off-by: Zhou Chengming --- kernel/livepatch/core.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c index af46438..b4b8bb0 100644 --- a/kernel/livepatch/core.c +++ b/kernel/livepatch/core.c @@ -182,7 +182,10 @@ static int klp_find_object_symbol(const char *objname, const char *name, }; mutex_lock(&module_mutex); - kallsyms_on_each_symbol(klp_find_callback, &args); + if (objname) + module_kallsyms_on_each_symbol(klp_find_callback, &args); + else + kallsyms_on_each_symbol(klp_find_callback, &args); mutex_unlock(&module_mutex); /* -- 1.8.3.1