From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mails.dpdk.org (mails.dpdk.org [217.70.189.124]) by smtp.lore.kernel.org (Postfix) with ESMTP id 88C15108B907 for ; Fri, 20 Mar 2026 11:57:24 +0000 (UTC) Received: from mails.dpdk.org (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id 50174402B2; Fri, 20 Mar 2026 12:57:23 +0100 (CET) Received: from inbox.dpdk.org (inbox.dpdk.org [95.142.172.178]) by mails.dpdk.org (Postfix) with ESMTP id 8761640272 for ; Fri, 20 Mar 2026 12:57:21 +0100 (CET) Received: by inbox.dpdk.org (Postfix, from userid 33) id 6B9184AD54; Fri, 20 Mar 2026 12:57:21 +0100 (CET) From: bugzilla@dpdk.org To: dev@dpdk.org Subject: [wishes/any Bug 1906] Use DPDK memory for lcore variables Date: Fri, 20 Mar 2026 11:57:21 +0000 X-Bugzilla-Reason: AssignedTo X-Bugzilla-Type: new X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: wishes X-Bugzilla-Component: any X-Bugzilla-Version: unspecified X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: mb@smartsharesystems.com X-Bugzilla-Status: UNCONFIRMED X-Bugzilla-Resolution: X-Bugzilla-Priority: Normal X-Bugzilla-Assigned-To: dev@dpdk.org X-Bugzilla-Target-Milestone: --- X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: bug_id short_desc product version rep_platform op_sys bug_status bug_severity priority component assigned_to reporter target_milestone bug_group Message-ID: Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 X-Bugzilla-URL: http://bugs.dpdk.org/ Auto-Submitted: auto-generated X-Auto-Response-Suppress: All MIME-Version: 1.0 X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org http://bugs.dpdk.org/show_bug.cgi?id=3D1906 Bug ID: 1906 Summary: Use DPDK memory for lcore variables Product: wishes Version: unspecified Hardware: All OS: All Status: UNCONFIRMED Severity: normal Priority: Normal Component: any Assignee: dev@dpdk.org Reporter: mb@smartsharesystems.com Target Milestone: --- Group: wishes-managers Goal: Use DPDK memory for lcore variables Benefits: 1. lcore variables are stored in hugepages, with fewer TLB misses 2. lcore variables could be shared with secondary process Means: Compared to (RTE_CACHE_GUARD'ed) arrays indexed by lcore id, the main benef= it of lcore variables is that the variables can share the same CPU cache line, which improves CPU cache efficiency. The effect of cache line sharing depends on the size of the variable. Multiple small variables can share the same CPU cache line. Variables spanning multiple CPU cache lines have a smaller degree of overlap within CPU cache lines. Memory for lcore variables is allocated in chunks of RTE_MAX_LCORE_VAR * RTE_MAX_LCORE bytes, where RTE_MAX_LCORE_VAR is the max size of an lcore variable. The default RTE_MAX_LCORE_VAR is 128 KB. If using mlockall() to pin RAM to the DPDK application, the benefits of usi= ng the standard heap with normal 4 KB pages for lcore variables - not using mo= re RAM than actually used by lcore variables (regardless of the size of the me= mory chunks allocated for lcore variables) - disappears. Since lcore variables' benefit of CPU cache line sharing decreases when the lcore variables are large, it would be reasonable to reduce the max size of lcore variables (RTE_MAX_LCORE_VAR) significantly, and recommend using other methods for storing large per-lcore variables. --=20 You are receiving this mail because: You are the assignee for the bug.=