From: Chao Gao <chao.gao@intel.com>
To: linux-kernel@vger.kernel.org, iommu@lists.linux.dev
Cc: dave.hansen@intel.com, len.brown@intel.com, tony.luck@intel.com,
rafael.j.wysocki@intel.com, reinette.chatre@intel.com,
dan.j.williams@intel.com, kirill.shutemov@linux.intel.com,
sathyanarayanan.kuppuswamy@linux.intel.com,
ilpo.jarvinen@linux.intel.com, ak@linux.intel.com,
alexander.shishkin@linux.intel.com, Chao Gao <chao.gao@intel.com>
Subject: [RFC v2 0/2] swiotlb performance optimizations
Date: Mon, 18 Jul 2022 09:28:16 +0800 [thread overview]
Message-ID: <20220718012818.107051-1-chao.gao@intel.com> (raw)
Intent of this post:
Seek reviews from Intel reviewers and anyone else in the list
interested in IO performance in confidential VMs. Need some acked-by
reviewed-by tags before I can add swiotlb maintainers to "to/cc" lists
and ask for a review from them.
Changes from v1 to v2:
- rebase to the latest dma-mapping tree.
- drop the duplicate patch for mitigating lock contention
- re-collect perf data
swiotlb is now widely used by confidential VMs. This series optimizes
swiotlb to reduce cache misses and lock contention during bounce buffer
allocation/free and memory bouncing to improve IO workload performance in
confidential VMs.
Here are some FIO tests we did to demonstrate the improvement.
Test setup
----------
A normal VM with 8vCPU and 32G memory, swiotlb is enabled by swiotlb=force.
FIO block size is 4K and iodepth is 256. Note that a normal VM is used so
that others lack of necessary hardware to host confidential VMs can reproduce
results below.
Results
-------
1 FIO job read/write IOPS (k)
vanilla read 216
write 251
optimized read 250
write 270
1-job FIO sequential read/write perf increase by 19% and 8% respectively.
Chao Gao (2):
swiotlb: use bitmap to track free slots
swiotlb: Allocate memory in a cache-friendly way
include/linux/swiotlb.h | 8 ++-
kernel/dma/swiotlb.c | 127 +++++++++++++++++-----------------------
2 files changed, 60 insertions(+), 75 deletions(-)
--
2.25.1
next reply other threads:[~2022-07-18 1:28 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-18 1:28 Chao Gao [this message]
2022-07-18 1:28 ` [RFC v2 1/2] swiotlb: use bitmap to track free slots Chao Gao
2022-07-18 1:28 ` [RFC v2 2/2] swiotlb: Allocate memory in a cache-friendly way Chao Gao
2022-08-05 19:55 ` [RFC v2 0/2] swiotlb performance optimizations Chao Gao
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