From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 85AAE2248A0; Tue, 9 Dec 2025 13:48:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765288141; cv=none; b=BH6BJ9MqMIEZXR/UIosLl99IOF7hxHAa4g00BvMyg67EJlNjYQC5EHnzNV/3MzMK3RMpMwuT+ngrqgsdzExXVccjON+B6/ILPHYEavQeCNAjkuzUIyhR5hR3NECZWmzukdYOify4y7QAXxKN6qPscUg3JPSqXYOyLNImhKZxVeo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765288141; c=relaxed/simple; bh=FVuQRujYf++BNgQ6+PI/6/zZw0Q2ZkUFz3N/E8zTCx0=; h=Message-ID:Date:MIME-Version:Subject:To:References:From: In-Reply-To:Content-Type; b=hI411ngCLBvzPzqKKY7urU/senu5V2p7UqYQ46jUIjb853R6kaz3dj2Y0TYFqEazFP4AfGyDzIoccfqECzgv/Nir3mPRHvr96PuAlWaI2MLV16P38WLszsJKz8nLpj3PWiEScrXPodm3Cm8WnTOIN4a6mbPLSzxp/z1XT/pLTzs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 99A52175A; Tue, 9 Dec 2025 05:48:51 -0800 (PST) Received: from [10.57.45.100] (unknown [10.57.45.100]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 5B3343F762; Tue, 9 Dec 2025 05:48:54 -0800 (PST) Message-ID: Date: Tue, 9 Dec 2025 14:48:51 +0100 Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v9 15/16] entry: Inline syscall_exit_work() To: Jinjie Ruan , catalin.marinas@arm.com, will@kernel.org, oleg@redhat.com, tglx@linutronix.de, peterz@infradead.org, luto@kernel.org, shuah@kernel.org, kees@kernel.org, wad@chromium.org, deller@gmx.de, macro@orcam.me.uk, charlie@rivosinc.com, ldv@strace.io, mark.rutland@arm.com, song@kernel.org, ryan.roberts@arm.com, ada.coupriediaz@arm.com, anshuman.khandual@arm.com, broonie@kernel.org, pengcan@kylinos.cn, dvyukov@google.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org References: <20251204082123.2792067-1-ruanjinjie@huawei.com> <20251204082123.2792067-16-ruanjinjie@huawei.com> From: Kevin Brodsky Content-Language: en-GB In-Reply-To: <20251204082123.2792067-16-ruanjinjie@huawei.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 04/12/2025 09:21, Jinjie Ruan wrote: > After switch arm64 to Generic Entry, a new hotspot syscall_exit_work() > appeared because syscall_exit_work() is no longer inlined. so inline Before this series the call to syscall_trace_exit() in el0_svc_common() could not be inlined, so "no longer inlined" doesn't seem to be accurate. > syscall_exit_work(), and it has 2.6% performance uplift on perf bench > basic syscall on kunpeng920 as below. That seems strange. syscall_exit_work() is only called if some flag in SYSCALL_WORK_EXIT is set, which means that we're doing something special like tracing. That shouldn't be the case when running a simple perf bench syscall. Also worth nothing that its counterpart (syscall_trace_enter())) is not currently inlined, the asymmetry would have to be justified. > | Metric | W/O this patch | With this patch | Change | > | ---------- | -------------- | --------------- | --------- | > | Total time | 2.171 [sec] | 2.114 [sec] | ↓2.6% | > | usecs/op | 0.217192 | 0.211453 | ↓2.6% | > | ops/sec | 4,604,225 | 4,729,178 | ↑2.7% | > > Signed-off-by: Jinjie Ruan > --- > include/linux/entry-common.h | 63 ++++++++++++++++++++++++++++++++++- > kernel/entry/syscall-common.c | 59 ++------------------------------ These changes are purely generic, surely all architectures using GENERIC_ENTRY should get similar benefits (assuming LTO isn't used)? > 2 files changed, 64 insertions(+), 58 deletions(-) > > diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h > index cd6dacb2d8bf..2f84377fb016 100644 > --- a/include/linux/entry-common.h > +++ b/include/linux/entry-common.h > @@ -2,6 +2,7 @@ > #ifndef __LINUX_ENTRYCOMMON_H > #define __LINUX_ENTRYCOMMON_H > > +#include > #include > #include > #include > @@ -128,6 +129,41 @@ static __always_inline long syscall_enter_from_user_mode(struct pt_regs *regs, l > return ret; > } > > +/* > + * If SYSCALL_EMU is set, then the only reason to report is when > + * SINGLESTEP is set (i.e. PTRACE_SYSEMU_SINGLESTEP). This syscall > + * instruction has been already reported in syscall_enter_from_user_mode(). > + */ > +static __always_inline bool report_single_step(unsigned long work) > +{ > + if (work & SYSCALL_WORK_SYSCALL_EMU) > + return false; > + > + return work & SYSCALL_WORK_SYSCALL_EXIT_TRAP; > +} > + > +/** > + * arch_ptrace_report_syscall_exit - Architecture specific > + * ptrace_report_syscall_exit. > + * > + * Invoked from syscall_exit_work() to wrap ptrace_report_syscall_exit(). > + * > + * The main purpose is to support arch-specific ptrace_report_syscall_exit > + * implementation. > + */ > +static __always_inline void arch_ptrace_report_syscall_exit(struct pt_regs *regs, > + int step); > + > +#ifndef arch_ptrace_report_syscall_exit > +static __always_inline void arch_ptrace_report_syscall_exit(struct pt_regs *regs, > + int step) > +{ > + ptrace_report_syscall_exit(regs, step); > +} > +#endif If we want syscall_exit_work() to be inline, then why would we define this hook in syscall-common.c in patch 12? Might as well define both hooks in entry-common.h right away and avoid some noise here. - Kevin > [...]