<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <meta name="ProgId" content="Word.Document"> <meta name="Generator" content="Microsoft Word 15"> <meta name="Originator" content="Microsoft Word 15"> <link rel="File-List" href="cid:filelist.xml@01DC57C0.D2AE2E00"><link rel="Edit-Time-Data" href="cid:editdata.mso"><style></style> </head> <body lang="EN-US" link="blue" vlink="purple" style="tab-interval:.5in;word-wrap:break-word"> <div class="WordSection1"> Hi,<o:p></o:p> I suppose you mean some sort of user-provided alloc()/free() callbacks that<o:p></o:p> will be used by ACL lib at generate phase?<o:p></o:p> And I presume if none provided, by default it will fall-back to rte_malloc/rte_free?<o:p></o:p> If so, then yes, sounds reasonable.<o:p></o:p> Patches are welcomed :)<o:p></o:p> Konstantin<o:p></o:p> <o:p> </o:p> <div style="border:none;border-left:solid blue 1.5pt;padding:0in 0in 0in 4.0pt"> <div> <div style="border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in"> From: mannywang(王永峰) <mannywang@tencent.com> Sent: Friday, November 14, 2025 2:52 AM To: dev <dev@dpdk.org> Cc: konstantin.v.ananyev <konstantin.v.ananyev@yandex.ru> Subject: [RFC] rte_acl_build memory fragmentation concern and proposal for external memory support<o:p></o:p> </div> </div> <o:p> </o:p> <div> <div id="wemail_placeholder_space"> <div> <h2 style="background:white">Problem Statement<o:p></o:p></h2> <p style="background:white;margin:0.75rem;font-variant-numeric: normal;font-variant-east-asian: normal;font-variant-alternates: normal;font-size-adjust: none;font-kerning: auto;font-optical-sizing: auto;font-feature-settings: normal;font-variation-settings: normal;font-variant-position: normal;font-stretch: normal;overflow-wrap: break-word;white-space-collapse: break-spaces"> Hello DPDK community,<o:p></o:p> <p style="background:white;margin:0.75rem;font-variant-numeric: normal;font-variant-east-asian: normal;font-variant-alternates: normal;font-size-adjust: none;font-kerning: auto;font-optical-sizing: auto;font-feature-settings: normal;font-variation-settings: normal;font-variant-position: normal;font-stretch: normal;overflow-wrap: break-word;white-space-collapse: break-spaces"> We've been using DPDK's ACL library in a long-running network application and observed a concerning issue regarding memory fragmentation. The <code>rte_acl_build()</code>function internally uses <code>rte_zmalloc_socket()</code>for dynamic memory allocation during ACL rule compilation.<o:p></o:p> <p style="background:white;margin:0.75rem;font-variant-numeric: normal;font-variant-east-asian: normal;font-variant-alternates: normal;font-size-adjust: none;font-kerning: auto;font-optical-sizing: auto;font-feature-settings: normal;font-variation-settings: normal;font-variant-position: normal;font-stretch: normal;overflow-wrap: break-word;white-space-collapse: break-spaces"> While this design works well for short-lived processes, it creates challenges for long-running applications (days/weeks) where memory fragmentation becomes a critical concern. Each ACL rebuild (due to rule updates, configuration changes, etc.) allocates variable-sized memory blocks for the trie structures and transition tables, which are then freed when the ACL context is destroyed or rebuilt.<o:p></o:p> <p style="margin:0in;background:white;font-variant-numeric: normal;font-variant-east-asian: normal;font-variant-alternates: normal;font-size-adjust: none;font-kerning: auto;font-optical-sizing: auto;font-feature-settings: normal;font-variation-settings: normal;font-variant-position: normal;font-stretch: normal;overflow-wrap: break-word;white-space-collapse: break-spaces"> This pattern leads to:<o:p></o:p> <div> <div> 1. Memory fragmentation over time, as the heap accumulates "holes" of varying sizes<o:p></o:p> </div> <div> 2. Potential allocation failures even when total free memory appears sufficient<o:p></o:p> </div> <div style="margin-left:.25in;word-break:break-word;overflow-wrap: break-word;box-sizing: border-box"> 3. Difficulty in memory budgeting for deterministic systems<o:p></o:p> </div> </div> <h2 style="background:white;margin:1.75rem 0px;font-variant-numeric: normal;font-variant-east-asian: normal;font-variant-alternates: normal;font-size-adjust: none;font-kerning: auto;font-optical-sizing: auto;font-feature-settings: normal;font-variation-settings: normal;font-variant-position: normal;font-stretch: normal;font-size:1.125rem"> Current Limitation<o:p></o:p></h2> <p style="background:white;margin:0.75rem;font-variant-numeric: normal;font-variant-east-asian: normal;font-variant-alternates: normal;font-size-adjust: none;font-kerning: auto;font-optical-sizing: auto;font-feature-settings: normal;font-variation-settings: normal;font-variant-position: normal;font-stretch: normal;overflow-wrap: break-word;white-space-collapse: break-spaces"> The current API doesn't allow applications to provide pre-allocated memory for ACL construction, forcing dynamic allocations that contribute to heap fragmentation. This is particularly problematic for applications that prioritize long-term stability and predictable memory usage.<o:p></o:p> <h2 style="background:white;margin:1.75rem 0px;font-variant-numeric: normal;font-variant-east-asian: normal;font-variant-alternates: normal;font-size-adjust: none;font-kerning: auto;font-optical-sizing: auto;font-feature-settings: normal;font-variation-settings: normal;font-variant-position: normal;font-stretch: normal;font-size:1.125rem"> Proposed Solution<o:p></o:p></h2> <p style="background:white;margin:0.75rem;font-variant-numeric: normal;font-variant-east-asian: normal;font-variant-alternates: normal;font-size-adjust: none;font-kerning: auto;font-optical-sizing: auto;font-feature-settings: normal;font-variation-settings: normal;font-variant-position: normal;font-stretch: normal;overflow-wrap: break-word;white-space-collapse: break-spaces"> We propose extending the ACL API to support external memory buffers for the build process. This would allow applications to manage memory allocation strategies according to their specific requirements (pool-based, static allocation, etc.).<o:p></o:p> </div> </div> <div> <o:p> </o:p> </div> <div id="wemailsigcontent"> <div class="MsoNormal" style="mso-margin-top-alt:5.25pt;margin-right:0in;margin-bottom:5.25pt;margin-left:0in"> <hr size="0" width="80" style="width:60.0pt" align="left"> </div> <a href="https://work.weixin.qq.com/wework_admin/user/h5/qqmail_user_card/vc879305fe5b6b5af3?from=myprofile" target="_blank">发自我的企业微信</a><o:p></o:p> <div> <o:p> </o:p> </div> <div> <o:p> </o:p> </div> </div> </div> </div> </div> </body> </html>