From: Thomas Gleixner <tglx@linutronix.de>
To: Dave Hansen <dave.hansen@intel.com>,
"Bae, Chang Seok" <chang.seok.bae@intel.com>
Cc: "Sang, Oliver" <oliver.sang@intel.com>,
Borislav Petkov <bp@suse.de>, LKML <linux-kernel@vger.kernel.org>,
"lkp@lists.01.org" <lkp@lists.01.org>, lkp <lkp@intel.com>,
"Huang, Ying" <ying.huang@intel.com>,
"Tang, Feng" <feng.tang@intel.com>,
"zhengjun.xing@linux.intel.com" <zhengjun.xing@linux.intel.com>,
"Yin, Fengwei" <fengwei.yin@intel.com>
Subject: Re: [x86/signal] 3aac3ebea0: will-it-scale.per_thread_ops -11.9% regression
Date: Thu, 09 Dec 2021 09:13:18 +0100 [thread overview]
Message-ID: <87v8zyyz4x.ffs@tglx> (raw)
In-Reply-To: <c94b8394-08cd-8273-2cd5-1ee5880d4c36@intel.com>
On Wed, Dec 08 2021 at 10:20, Dave Hansen wrote:
> On 12/8/21 10:00 AM, Bae, Chang Seok wrote:
>> diff --git a/kernel/signal.c b/kernel/signal.c
>> index a629b11bf3e0..8194d2f38bf1 100644
>> --- a/kernel/signal.c
>> +++ b/kernel/signal.c
>> @@ -4224,6 +4224,11 @@ int restore_altstack(const stack_t __user *uss)
>> stack_t new;
>> if (copy_from_user(&new, uss, sizeof(stack_t)))
>> return -EFAULT;
>> + if (current->sas_ss_sp == (unsigned long) new.ss_sp &&
>> + current->sas_ss_size == new.ss_size &&
>> + current->sas_ss_flags == new.ss_flags)
>> + return 0;
>> +
>> (void)do_sigaltstack(&new, NULL, current_user_stack_pointer(),
>> MINSIGSTKSZ);
>> /* squash all but EFAULT for now */
>
> This seems like a generally good optimization that could go in
> do_sigaltstack() itself, no?
Yes, right before the sigaltstack_lock() invocation.
Thanks,
tglx
next prev parent reply other threads:[~2021-12-09 8:13 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-07 1:21 [x86/signal] 3aac3ebea0: will-it-scale.per_thread_ops -11.9% regression kernel test robot
2021-12-07 1:44 ` Oliver Sang
2021-12-07 13:38 ` Thomas Gleixner
2021-12-07 18:49 ` Bae, Chang Seok
2021-12-07 20:36 ` Thomas Gleixner
2021-12-07 22:17 ` Bae, Chang Seok
2021-12-08 0:59 ` Yin Fengwei
2021-12-09 2:30 ` [LKP] " Carel Si
2021-12-07 23:14 ` Dave Hansen
2021-12-08 18:00 ` Bae, Chang Seok
2021-12-08 18:20 ` Dave Hansen
2021-12-08 19:14 ` Thomas Gleixner
2021-12-09 8:13 ` Thomas Gleixner [this message]
2021-12-10 4:15 ` [LKP] " Carel Si
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=87v8zyyz4x.ffs@tglx \
--to=tglx@linutronix.de \
--cc=bp@suse.de \
--cc=chang.seok.bae@intel.com \
--cc=dave.hansen@intel.com \
--cc=feng.tang@intel.com \
--cc=fengwei.yin@intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=lkp@intel.com \
--cc=lkp@lists.01.org \
--cc=oliver.sang@intel.com \
--cc=ying.huang@intel.com \
--cc=zhengjun.xing@linux.intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox