From mboxrd@z Thu Jan 1 00:00:00 1970 From: guohanjun@huawei.com (Hanjun Guo) Date: Wed, 31 Jan 2018 20:45:56 +0800 Subject: [PATCH v3 0/6] 32bit ARM branch predictor hardening In-Reply-To: References: <20180125152139.32431-1-marc.zyngier@arm.com> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 2018/1/29 22:58, Nishanth Menon wrote: > On Mon, Jan 29, 2018 at 5:36 AM, Hanjun Guo wrote: > [...] > >> By the way, this patch set just enable branch predictor hardening >> on arm32 unconditionally, but some of machines (such as wireless >> network base station) will not be exposed to user to take advantage >> of variant 2, and those machines will be pretty sensitive for >> performance, so can we introduce Kconfig or boot option to disable >> branch predictor hardening as an option? > > I am curious: Have you seen performance degradation with this series? > If yes, is it possible to share the information? Sorry for the late reply, the performance data for context switch (CFS) is about 6%~12% drop (A9 based machine) for the first around test, but the data is not stable, I need to retest then I will update here. Thanks Hanjun