From: Zhen Lei <thunder.leizhen@huawei.com>
To: Robin Murphy <robin.murphy@arm.com>,
Will Deacon <will.deacon@arm.com>, Joerg Roedel <joro@8bytes.org>,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
iommu <iommu@lists.linux-foundation.org>,
linux-kernel <linux-kernel@vger.kernel.org>
Cc: Zhen Lei <thunder.leizhen@huawei.com>,
LinuxArm <linuxarm@huawei.com>, Hanjun Guo <guohanjun@huawei.com>,
Libin <huawei.libin@huawei.com>,
"John Garry" <john.garry@huawei.com>
Subject: [PATCH v3 0/2] bugfix and optimization about CMD_SYNC
Date: Wed, 15 Aug 2018 18:23:00 +0800 [thread overview]
Message-ID: <1534328582-17664-1-git-send-email-thunder.leizhen@huawei.com> (raw)
v2 -> v3:
Although I have no data to show how many performance will be impacted
because of arm_smmu_cmdq_build_cmd is protected by spinlock. But it's
clear that the performance is bound to drop, a memset operation and
a complicate switch..case in the function arm_smmu_cmdq_build_cmd.
v1 -> v2:
1. move the call to arm_smmu_cmdq_build_cmd into the critical section,
and keep itself unchange.
2. Although patch2 can make sure no two CMD_SYNCs will be adjacent,
but patch1 is still needed, see below:
cpu0 cpu1 cpu2
msidata=0
msidata=1
insert cmd1
insert a TLBI command
insert cmd0
smmu execute cmd1
smmu execute TLBI
smmu execute cmd0
poll timeout, because msidata=1 is overridden by
cmd0, that means VAL=0, sync_idx=1.
Zhen Lei (2):
iommu/arm-smmu-v3: fix unexpected CMD_SYNC timeout
iommu/arm-smmu-v3: avoid redundant CMD_SYNCs if possible
drivers/iommu/arm-smmu-v3.c | 30 +++++++++++++++++++++++++-----
1 file changed, 25 insertions(+), 5 deletions(-)
--
1.8.3
next reply other threads:[~2018-08-15 10:23 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-15 10:23 Zhen Lei [this message]
2018-08-15 10:23 ` [PATCH v3 1/2] iommu/arm-smmu-v3: fix unexpected CMD_SYNC timeout Zhen Lei
2018-08-15 12:26 ` Robin Murphy
2018-08-15 13:00 ` Will Deacon
2018-08-15 18:08 ` John Garry
2018-08-16 4:11 ` Leizhen (ThunderTown)
2018-08-16 8:21 ` Leizhen (ThunderTown)
2018-08-16 9:18 ` Will Deacon
2018-08-16 9:27 ` Robin Murphy
2018-08-19 7:02 ` Leizhen (ThunderTown)
2018-09-05 1:46 ` Leizhen (ThunderTown)
2018-08-15 10:23 ` [PATCH v3 2/2] iommu/arm-smmu-v3: avoid redundant CMD_SYNCs if possible Zhen Lei
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