Received-SPF: pass (google.com: domain of linux-kernel+bounces-197602-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.199.223 as permitted sender) client-ip=147.75.199.223;
Date: Fri, 31 May 2024 16:44:16 -0700
From: Roman Gushchin <roman.gushchin@linux.dev>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Akinobu Mita <akinobu.mita@gmail.com>, Christoph Lameter <cl@linux.com>,
	David Rientjes <rientjes@google.com>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>,
	"Naveen N. Rao" <naveen.n.rao@linux.ibm.com>,
	Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>,
	"David S. Miller" <davem@davemloft.net>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Mark Rutland <mark.rutland@arm.com>, Jiri Olsa <jolsa@kernel.org>,
	Hyeonggon Yoo <42.hyeyoo@gmail.com>, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org, bpf@vger.kernel.org,
	linux-trace-kernel@vger.kernel.org
Subject: Re: [PATCH RFC 3/4] mm, slab: add static key for should_failslab()
Message-ID: <Zlpg0OFOsOSxrh9I@P9FQF9L96D.corp.robot.car>
References: <20240531-fault-injection-statickeys-v1-0-a513fd0a9614@suse.cz>
 <20240531-fault-injection-statickeys-v1-3-a513fd0a9614@suse.cz>
Precedence: bulk
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20240531-fault-injection-statickeys-v1-3-a513fd0a9614@suse.cz>

On Fri, May 31, 2024 at 11:33:34AM +0200, Vlastimil Babka wrote:
> Since commit 4f6923fbb352 ("mm: make should_failslab always available for
> fault injection") should_failslab() is unconditionally a noinline
> function. This adds visible overhead to the slab allocation hotpath,
> even if the function is empty. With CONFIG_FAILSLAB=y there's additional
> overhead when the functionality is not enabled by a boot parameter or
> debugfs.
> 
> The overhead can be eliminated with a static key around the callsite.
> Fault injection and error injection frameworks can now be told that the
> this function has a static key associated, and are able to enable and
> disable it accordingly.
> 
> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>

Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev>