Date: Mon, 17 Apr 2017 19:04:04 +0000 From: bugzilla-noreply@freebsd.org To: freebsd-standards@FreeBSD.org Subject: [Bug 218622] libc/gen/telldir [hack-n-PATCH] performance limited to O(n) vs file count, O(n^2) against samba ls workload Message-ID: <bug-218622-15-xdcMiem58z@https.bugs.freebsd.org/bugzilla/> In-Reply-To: <bug-218622-15@https.bugs.freebsd.org/bugzilla/> References: <bug-218622-15@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D218622 --- Comment #5 from commit-hook@freebsd.org --- A commit references this bug: Author: mav Date: Mon Apr 17 19:03:31 UTC 2017 New revision: 317064 URL: https://svnweb.freebsd.org/changeset/base/317064 Log: Optimize pathologic case of telldir() for Samba. When application reads large directory, calling telldir() for each entry, like Samba does, it creates exponential performance drop as number of entries reach tenths to hundreds of thousands. It is caused by full sear= ch through the internal list, that never finds matches in that scenario, but creates O(n^2) delays. This patch optimizes that search, limiting it to entries of the same buffer, turning time closer to O(n) in case of linear directory scan. PR: 218622 Reviewed by: jhb, jilles MFC after: 2 weeks Sponsored by: iXsystems, Inc. Differential Revision: https://reviews.freebsd.org/D10408 Changes: head/lib/libc/gen/telldir.c --=20 You are receiving this mail because: You are the assignee for the bug.=
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