Date: Wed, 2 Jun 2004 07:12:34 -0700 From: Bosko Milekic <bmilekic@FreeBSD.org> To: Gleb Smirnoff <glebius@cell.sick.ru> Cc: freebsd-current@freebsd.org Subject: Re: [HEADS-UP] mbuma is in the tree Message-ID: <20040602141234.GA33162@freefall.freebsd.org>
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> Bosko, [deletia] > are you going to convert mbuf tag allocator to UMA? Now >tags are allocated with malloc(). AFAIK, tags are used heavily in pf, >and forthcoming ALTQ. Moving to UMA should affect their performance >positively. First off, malloc() *is* UMA. With mbuma in the tree, I don't believe we have any remaining custom-allocators in the tree. As for what to do with m_tags, it is still unclear to me. Personally, I'm conflicted about their use. On one hand, they offer a clean way to attach metadata to packets, but on the other hand they are quite expensive. If you read the paper on mbuma, you'll notice that I point out that it would be worth investigating whether, in scenarios where an m_tag is ALWAYS required per packet (e.g., MAC), providing a secondary zone with pre-allocated m_tags for packet headers might be worth it. Prior to this work, however, I suggest we investigate the possibility of using smaller mini-mbufs whenever clusters are used so that space wastage is reduced. -Bosko
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