<story><title>AMD Ryzen Threadripper 3960X and 3970X Review</title><url>https://www.anandtech.com/print/15044/the-amd-ryzen-threadripper-3960x-and-3970x-review-24-and-32-cores-on-7nm</url></story><parent_chain><item><author>dnautics</author><text>Is avx512 an advantage really?  Iirc the machine has to go into another mode where processing across the board becomes slower except for the avx instructions, which to me seems only useful for niche hpc &amp;quot;measuring contest&amp;quot; applications.</text></item><item><author>bitL</author><text>The only advantages are AVX512 and optimized Intel compiler&amp;#x2F;libraries now.</text></item><item><author>shantara</author><text>The biggest indicator of the success of AMD Threadripper line to me is that Intel has been forced to cut the price of their newly released i9-10980XE CPU by $1000 compared to i9-9980XE while maintaining practically indistinguishable performance.</text></item></parent_chain><comment><author>robocat</author><text>AVX on Intel can have unobvious performance degradation: a single AVX512 instruction runs at ¼ speed[1] until the core downclocks, and it stays downclocked for 2ms (severely affecting mixed loads). The downclock apparently takes 500us[2] (edit: fact check? This seems unbelievable), and the CPU is idle until it restabilises.&lt;p&gt;If AMD have made different choices about AVX implementation, then benchmarking becomes difficult.&lt;p&gt;Intel benchmarks for sustained AVX512 load (HPC measuring contests) cannot be used to extrapolate for normal mixed loads (single or or short bursts of AVX512 instructions).&lt;p&gt;Edit: are there better links on the true costs of AVX512?&lt;p&gt;[1] &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;lemire.me&amp;#x2F;blog&amp;#x2F;2018&amp;#x2F;09&amp;#x2F;07&amp;#x2F;avx-512-when-and-how-to-use-these-new-instructions&amp;#x2F;&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;lemire.me&amp;#x2F;blog&amp;#x2F;2018&amp;#x2F;09&amp;#x2F;07&amp;#x2F;avx-512-when-and-how-to-us...&lt;/a&gt;&lt;p&gt;[2] &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;news.ycombinator.com&amp;#x2F;item?id=21031905&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;news.ycombinator.com&amp;#x2F;item?id=21031905&lt;/a&gt;&lt;p&gt;Also see: &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;blog.cloudflare.com&amp;#x2F;on-the-dangers-of-intels-frequency-scaling&amp;#x2F;&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;blog.cloudflare.com&amp;#x2F;on-the-dangers-of-intels-frequen...&lt;/a&gt;</text></comment>
<story><title>AMD Ryzen Threadripper 3960X and 3970X Review</title><url>https://www.anandtech.com/print/15044/the-amd-ryzen-threadripper-3960x-and-3970x-review-24-and-32-cores-on-7nm</url></story><parent_chain><item><author>dnautics</author><text>Is avx512 an advantage really?  Iirc the machine has to go into another mode where processing across the board becomes slower except for the avx instructions, which to me seems only useful for niche hpc &amp;quot;measuring contest&amp;quot; applications.</text></item><item><author>bitL</author><text>The only advantages are AVX512 and optimized Intel compiler&amp;#x2F;libraries now.</text></item><item><author>shantara</author><text>The biggest indicator of the success of AMD Threadripper line to me is that Intel has been forced to cut the price of their newly released i9-10980XE CPU by $1000 compared to i9-9980XE while maintaining practically indistinguishable performance.</text></item></parent_chain><comment><author>crote</author><text>From a developer perspective, yes. If you&amp;#x27;re manually writing  AVX intrinsics instead of just relying on the compiler, AVX512 is quite exciting due to the added mask registers, allowing you to exclude certain elements of your vector from the operation.
You can archieve this in AVX2, but it&amp;#x27;s quite painful.&lt;p&gt;Example:
Let&amp;#x27;s say that, for whatever reason, you have a vector struct containing 3 doubles, and another 64 bits of arbitrary data. Now, if you want to add those vectors together, keeping the arbitrary data of one element, that&amp;#x27;s quite difficult to do with AVX2. In AVX512, you can just set the bits of the mask to zero to exclude them from the operation, making it trivial.</text></comment>