{"id":285804,"date":"2026-07-04T06:09:00","date_gmt":"2026-07-04T10:09:00","guid":{"rendered":"https:\/\/news-you-need.com\/index.php\/2026\/07\/04\/linux-7-2-rc2-raising-the-default-risc-v-64-bit-cpu-limit-to-256-cores\/"},"modified":"2026-07-04T18:30:09","modified_gmt":"2026-07-04T22:30:09","slug":"linux-7-2-rc2-raising-the-default-risc-v-64-bit-cpu-limit-to-256-cores","status":"publish","type":"post","link":"https:\/\/news-you-need.com\/index.php\/2026\/07\/04\/linux-7-2-rc2-raising-the-default-risc-v-64-bit-cpu-limit-to-256-cores\/","title":{"rendered":"Linux 7.2-rc2 Raising The Default RISC-V 64-bit CPU Limit To 256 Cores"},"content":{"rendered":"<p><a href=\"https:\/\/www.phoronix.com\/news\/Linux-7.2-RISC-V-256-Cores\">Linux 7.2-rc2 Raising The Default RISC-V 64-bit CPU Limit To 256 Cores<\/a><\/p>\n<p><a href=\"https:\/\/www.phoronix.com\/news\/Linux-7.2-RISC-V-256-Cores\">https:\/\/www.phoronix.com\/news\/Linux-7.2-RISC-V-256-Cores<\/a><\/p>\n<p>Publish Date: <a href=\"publish_date]\">2026-07-04 06:09:00<\/a><\/p>\n<p>Source Domain: <a href=\"www.phoronix.com\">www.phoronix.com<\/a><\/p>\n<p>A post merge-window change that landed in Linux Git overnight ahead of tomorrow&#8217;s Linux 7.2-rc2 release is bumping the default limit on the number of supported CPU cores for RISC-V 64-bit. Now by default Linux will support up to 256 cores with RISC-V 64-bit kernel builds.<\/p>\n<p>Up to now RISC-V 64-bit has maintained a NR_CPUS value of 64 for the number of CPU cores to be supported. But merged to Git for Linux 7.2 that default threshold has been bumped to 256 cores\/threads. The NR_CPUS value in turn impacts the size of various static memory allocations and as that number goes higher does slightly increase kernel memory consumption. Meanwhile over on Linux x86_64, most distribution vendor kernels with MAXSMP enabled see NR_CPUS up at 8192 to deal with today&#8217;s high core count AMD and Intel server processors. AArch64 (ARM64) even has 512 for its NR_CPUS value or 2048 for LoongArch.<br \/>\n<\/p>\n<p align=\"center\"><img decoding=\"async\" src=\"https:\/\/www.phoronix.net\/image.php?id=2026&#038;image=riscv_256_cores\" alt=\"RISC-V 256 core limit\"\/><\/p>\n<p>Raising the NR_CPUS for RISC-V came at the request of SpacemiT. The commit bumping the limit explained:<br \/>\n<br \/>&#8220;SpacemiT has already produced a 80-core RVA23 RISC-V server, and going further back, the dual-socket SG2042-based Sophgo Pisces has 128 cores (although that had some issues achieving mainline support). Therefore, an NR_CPUS of 64 is not enough.<\/p>\n<p>Raise default NR_CPUS to 256 for 64BIT (when !RISCV_SBI_V01, since very old firmware can&#8217;t support more than 64 cores). The number was picked as a power of two that is at least double the known max. I believe this should be the right balance between not wasting too much memory and not having to touch this too often.\n<\/p>\n<p>Ubuntu has already been shipping NR_CPUS=512 for riscv64. We have also been testing NR_CPUS=256 internally at ISCAS and found negligible performance impact and no ill effects.&#8221;<\/p>\n<p>The only surprising bit is that it was accepted post-merge-window by Linus Torvalds, granted, it shouldn&#8217;t have any real regression risk.<\/p>\n<p>That NR_CPUS increase was merged to Linux Git as part of this week&#8217;s RISC-V fixes.<\/p>\n<p><a href=\"https:\/\/www.phoronix.com\/news\/Linux-7.2-RISC-V-256-Cores\">Source<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Linux 7.2-rc2 Raising The Default RISC-V 64-bit CPU Limit To 256 Cores https:\/\/www.phoronix.com\/news\/Linux-7.2-RISC-V-256-Cores Publish Date:&#8230;<\/p>\n","protected":false},"author":1,"featured_media":285805,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"fifu_image_url":"https:\/\/www.phoronix.net\/image.php?id=2026&image=riscv_256_cores","fifu_image_alt":"","footnotes":""},"categories":[48],"tags":[71,79],"class_list":["post-285804","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-linux","tag-linux","tag-ubuntu"],"_links":{"self":[{"href":"https:\/\/news-you-need.com\/index.php\/wp-json\/wp\/v2\/posts\/285804"}],"collection":[{"href":"https:\/\/news-you-need.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/news-you-need.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/news-you-need.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/news-you-need.com\/index.php\/wp-json\/wp\/v2\/comments?post=285804"}],"version-history":[{"count":1,"href":"https:\/\/news-you-need.com\/index.php\/wp-json\/wp\/v2\/posts\/285804\/revisions"}],"predecessor-version":[{"id":285806,"href":"https:\/\/news-you-need.com\/index.php\/wp-json\/wp\/v2\/posts\/285804\/revisions\/285806"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/news-you-need.com\/index.php\/wp-json\/wp\/v2\/media\/285805"}],"wp:attachment":[{"href":"https:\/\/news-you-need.com\/index.php\/wp-json\/wp\/v2\/media?parent=285804"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/news-you-need.com\/index.php\/wp-json\/wp\/v2\/categories?post=285804"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/news-you-need.com\/index.php\/wp-json\/wp\/v2\/tags?post=285804"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}