Build Options for maximum performance of SHA256

[Martin Bonner]

> Date: Mon, 5 Feb 2024 09:48:21 +0100
> From: opensslmailing <mailto:opensslmailing at gmx.de>
> To: mailto:openssl-users at openssl.org
> Subject: Build Options for maximum performance of SHA256 digest
>       calculation
> Message-ID: <mailto:76163372.20240205094821 at gmx.de>
> Content-Type: text/plain; charset=us-ascii

> I want to build openssl for Windows to achieve best possible performance on
> my machine (Core i5 6500) of SHA256 digest calculation for large files in a
> C++ program. What options do I have to use to achieve this?

> P.S. Currently my program calculates about 330 Mibyte/s whereas other programs
> using OpenSSL reach about 400 MiByte/s on the same machine with the same file

I don't think this is really on-topic for this list, but some suggestions for
things to investigate:
- How big is the file?
- How are you reading the file (istream, fopen as text, fopen as binary, read,
  memory map)?
- How are the other programs reading it?
- What platform are you running on? What compiler are you using?
- When you build OpenSSL, are you specifying compiler flags to generate code for
  modern processors only?


Martin Bonner


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