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Date: Wed, 29 Mar 2017 12:40:41 -0700 From: Jessica Yu <jeyu@...hat.com> To: Zhou Chengming <zhouchengming1@...wei.com> Cc: live-patching@...r.kernel.org, linux-kernel@...r.kernel.org, jpoimboe@...hat.com, jikos@...nel.org, mbenes@...e.cz, pmladek@...e.com, huawei.libin@...wei.com Subject: Re: [PATCH v2] livepatch: Reduce the time of finding module symbols +++ Zhou Chengming [28/03/17 21:10 +0800]: >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 <zhouchengming1@...wei.com> Limiting the search space for symbol lookups is a valid improvement, so: Acked-by: Jessica Yu <jeyu@...hat.com> >--- > 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 > >-- >To unsubscribe from this list: send the line "unsubscribe live-patching" in >the body of a message to majordomo@...r.kernel.org >More majordomo info at http://vger.kernel.org/majordomo-info.html
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