From: Juergen Gross <jgross@suse.com>
To: Guo Hui <guohui@uniontech.com>, peterz@infradead.org
Cc: longman@redhat.com, srivatsa@csail.mit.edu, amakhalov@vmware.com,
pv-drivers@vmware.com, tglx@linutronix.de, mingo@redhat.com,
bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org,
hpa@zytor.com, will@kernel.org, boqun.feng@gmail.com,
virtualization@lists.linux-foundation.org,
wangxiaohua@uniontech.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4] x86/paravirt: useless assignment instructions cause Unixbench full core performance degradation
Date: Mon, 27 Jun 2022 17:42:41 +0200 [thread overview]
Message-ID: <85b1fc01-ff9b-7802-d624-1450c9b9bae5@suse.com> (raw)
In-Reply-To: <20220627142732.31067-1-guohui@uniontech.com>
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On 27.06.22 16:27, Guo Hui wrote:
> The instructions assigned to the vcpu_is_preempted function parameter
> in the X86 architecture physical machine are redundant instructions,
> causing the multi-core performance of Unixbench to drop by about 4% to 5%.
> The C function is as follows:
> static bool vcpu_is_preempted(long vcpu);
>
> The parameter 'vcpu' in the function osq_lock
> that calls the function vcpu_is_preempted is assigned as follows:
>
> The C code is in the function node_cpu:
> cpu = node->cpu - 1;
>
> The instructions corresponding to the C code are:
> mov 0x14(%rax),%edi
> sub $0x1,%edi
>
> The above instructions are unnecessary
> in the X86 Native operating environment,
> causing high cache-misses and degrading performance.
>
> This patch uses static_key to not execute this instruction
> in the Native runtime environment.
>
> The patch effect is as follows two machines,
> Unixbench runs with full core score:
>
> 1. Machine configuration:
> Intel(R) Xeon(R) Silver 4210 CPU @ 2.20GHz
> CPU core: 40
> Memory: 256G
> OS Kernel: 5.19-rc3
>
> Before using the patch:
> System Benchmarks Index Values BASELINE RESULT INDEX
> Dhrystone 2 using register variables 116700.0 948326591.2 81261.9
> Double-Precision Whetstone 55.0 211986.3 38543.0
> Execl Throughput 43.0 43453.2 10105.4
> File Copy 1024 bufsize 2000 maxblocks 3960.0 438936.2 1108.4
> File Copy 256 bufsize 500 maxblocks 1655.0 118197.4 714.2
> File Copy 4096 bufsize 8000 maxblocks 5800.0 1534674.7 2646.0
> Pipe Throughput 12440.0 46482107.6 37365.0
> Pipe-based Context Switching 4000.0 1915094.2 4787.7
> Process Creation 126.0 85442.2 6781.1
> Shell Scripts (1 concurrent) 42.4 69400.7 16368.1
> Shell Scripts (8 concurrent) 6.0 8877.2 14795.3
> System Call Overhead 15000.0 4714906.1 3143.3
> ========
> System Benchmarks Index Score 7923.3
>
> After using the patch:
> System Benchmarks Index Values BASELINE RESULT INDEX
> Dhrystone 2 using register variables 116700.0 947032915.5 81151.1
> Double-Precision Whetstone 55.0 211971.2 38540.2
> Execl Throughput 43.0 45054.8 10477.9
> File Copy 1024 bufsize 2000 maxblocks 3960.0 515024.9 1300.6
> File Copy 256 bufsize 500 maxblocks 1655.0 146354.6 884.3
> File Copy 4096 bufsize 8000 maxblocks 5800.0 1679995.9 2896.5
> Pipe Throughput 12440.0 46466394.2 37352.4
> Pipe-based Context Switching 4000.0 1898221.4 4745.6
> Process Creation 126.0 85653.1 6797.9
> Shell Scripts (1 concurrent) 42.4 69437.3 16376.7
> Shell Scripts (8 concurrent) 6.0 8898.9 14831.4
> System Call Overhead 15000.0 4658746.7 3105.8
> ========
> System Benchmarks Index Score 8248.8
>
> 2. Machine configuration:
> Hygon C86 7185 32-core Processor
> CPU core: 128
> Memory: 256G
> OS Kernel: 5.19-rc3
>
> Before using the patch:
> System Benchmarks Index Values BASELINE RESULT INDEX
> Dhrystone 2 using register variables 116700.0 2256644068.3 193371.4
> Double-Precision Whetstone 55.0 438969.9 79812.7
> Execl Throughput 43.0 10108.6 2350.8
> File Copy 1024 bufsize 2000 maxblocks 3960.0 275892.8 696.7
> File Copy 256 bufsize 500 maxblocks 1655.0 72082.7 435.5
> File Copy 4096 bufsize 8000 maxblocks 5800.0 925043.4 1594.9
> Pipe Throughput 12440.0 118905512.5 95583.2
> Pipe-based Context Switching 4000.0 7820945.7 19552.4
> Process Creation 126.0 31233.3 2478.8
> Shell Scripts (1 concurrent) 42.4 49042.8 11566.7
> Shell Scripts (8 concurrent) 6.0 6656.0 11093.3
> System Call Overhead 15000.0 6816047.5 4544.0
> ========
> System Benchmarks Index Score 7756.6
>
> After using the patch:
> System Benchmarks Index Values BASELINE RESULT INDEX
> Dhrystone 2 using register variables 116700.0 2252272929.4 192996.8
> Double-Precision Whetstone 55.0 451847.2 82154.0
> Execl Throughput 43.0 10595.1 2464.0
> File Copy 1024 bufsize 2000 maxblocks 3960.0 301279.3 760.8
> File Copy 256 bufsize 500 maxblocks 1655.0 79291.3 479.1
> File Copy 4096 bufsize 8000 maxblocks 5800.0 1039755.2 1792.7
> Pipe Throughput 12440.0 118701468.1 95419.2
> Pipe-based Context Switching 4000.0 8073453.3 20183.6
> Process Creation 126.0 33440.9 2654.0
> Shell Scripts (1 concurrent) 42.4 52722.6 12434.6
> Shell Scripts (8 concurrent) 6.0 7050.4 11750.6
> System Call Overhead 15000.0 6834371.5 4556.2
> ========
> System Benchmarks Index Score 8157.8
>
> Signed-off-by: Guo Hui <guohui@uniontech.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Juergen
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next prev parent reply other threads:[~2022-06-27 15:42 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-23 15:50 [PATCH] x86/paravirt: useless assignment instructions cause Unixbench full core performance degradation Guo Hui
2022-06-23 21:54 ` Waiman Long
2022-06-27 2:13 ` [PATCH v2] " Guo Hui
2022-06-27 3:02 ` Waiman Long
[not found] ` <62b94621.1c69fb81.3a378.57ccSMTPIN_ADDED_BROKEN@mx.google.com>
2022-06-27 13:25 ` Waiman Long
2022-06-27 5:57 ` Juergen Gross
2022-06-27 7:07 ` [PATCH v3] " Guo Hui
2022-06-27 7:49 ` [PATCH v2] " Peter Zijlstra
[not found] ` <3c020577-2045-fa12-9e33-65ece10bda30@uniontech.com>
2022-06-27 9:30 ` Peter Zijlstra
2022-06-27 14:27 ` [PATCH v4] " Guo Hui
2022-06-27 15:42 ` Juergen Gross [this message]
2022-06-27 15:58 ` Waiman Long
2022-06-28 4:31 ` [PATCH v5] " Guo Hui
2022-06-28 12:54 ` [PATCH v6] " Guo Hui
2022-06-28 14:15 ` Waiman Long
2022-06-28 16:12 ` [PATCH v7] " Guo Hui
2022-06-28 17:28 ` Waiman Long
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