Date:   Tue, 20 Sep 2022 09:31:01 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Yang Shen <shenyang39@...wei.com>
Cc:     herbert@...dor.apana.org.au, davem@...emloft.net,
        linux-kernel@...r.kernel.org, linux-crypto@...r.kernel.org
Subject: Re: [RFC PATCH 2/6] crypto: benchmark - add a crypto benchmark tool

On Mon, Sep 19, 2022 at 08:05:33PM +0800, Yang Shen wrote:
> Provide a crypto benchmark to help the developer quickly get the
> performance of a algorithm registered in crypto.
> 
> Due to the crypto algorithms have multifarious parameters, the tool
> cannot support all test scenes. In order to provide users with simple
> and easy-to-use tools and support as many test scenarios as possible,
> benchmark refers to the crypto method to provide a unified struct
> 'crypto_bm_ops'. And the algorithm registers its own callbacks to parse
> the user's input. In crypto, a algorithm class has multiple algorithms,
> but all of them uses the same API. So in the benchmark, a algorithm
> class uses the same 'ops' and distinguish specific algorithm by name.
> 
> First, consider the performance calculation model. Considering the
> crypto subsystem model, a reasonable process code based on crypto api
> should create a numa node based 'crypto_tfm' in advance and apply for
> a certain amount of 'crypto_req' according to their own business.
> In the real business processing stage, the thread send tasks based on
> 'crypto_req' and wait for completion.
> 
> Therefore, the benchmark will create 'crypto_tfm' and 'crypto_req' at
> first, and then count all requests time to calculate performance.
> So the result is the pure algorithm performance. When each algorithm
> class implements its own 'ops', it needs to pay attention to the content
> completed in the callback. Before the 'ops.perf', the tool had better
> prepare the request data set. And in order to avoid the false high
> performance of the algorithm caused by the false cache and TLB hit rate,
> the size of data set should be larger than 'crypto_req' number.
> The 'crypto_bm_ops' has following api:
>  - init & uninit
>  The initialize related functions. Algorithm can do some private setting.
>  - create_tfm & release_tfm
>  The 'crypto_tfm' related functions. Algorithm has different tfm name in
>  crypto. But they both has a member named tfm, so use tfm to stand for
>  algorithm handle. The benchmark has provides the tfm array.
>  - create_req & release_req
>  The 'crypto_req' related functions. The callbacks should create a 'reqnum'
>  'crypto_req' group in struct 'crypto_bm_base'. And the also suggest
>  prepare the request data in this function. In order to avoid the false
>  high performance of the algorithm caused by the false cache and TLB hit
>  rate, the size of data set should be larger than 'crypto_req' number.
>  - perf
>  The request sending functions. The registrant should use parameter 'loop'
>  to send requests repeatly. And update the count in struct
>  'crypto_bm_thread_data'.
> 
> Then consider the parameters that user can configure. Generally speaking,
> the following parameters will affect the performance of the algorithm:
> tfm number, request number, block size, numa node. And some parameters
> will affect the stability of performance: testing time and requests sent
> number. To sum up, the benchmark has following parameters:
>  - algorithm
>  The testing algorithm name. Showed in /proc/crypto.
>  - algtype
>  The testing algorithm class. Can get the algorithm class by echo 'algtype'
>  to /sys/module/crypto_benchmark/parameters/help.
>  - inputsize
>  The testing length that can greatly impact performance. Such as data size
>  for compress or key length for encryption.
>  - loop
>  The testing loop times. Avoid performance fluctuations caused by
>  environment.
>  - numamask
>  The testing bind numamask. Used for allocate memory, create threads and
>  create 'crypto_tfm'.
>  - optype
>  The testing algorithm operation type. Can get the algorithm available
>  operation types by cat /sys/module/crypto_benchmark/parameters/help
>  with specified 'algtype'.
>  - reqnum
>  The testing request number for per tfm. Used for test asynchrony api
>  performance.
>  - threadnum
>  The testing thread number. To simplify model, create a 'crypto_tfm' per
>  thread.
>  - time
>  The testing time. Used for stop the test thread.
>  - run
>  Start or stop the test.
> 
> Users can configure parameters under
> /sys/modules/crypto_benchmark/parameters/.

Please don't use module parameters for stuff like this, use configfs
which was designed for this type of interactions.

thanks,

greg k-h

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