Date: Fri, 15 Sep 2017 19:21:54 +0000 From: bugzilla-noreply@freebsd.org To: gecko@FreeBSD.org Subject: [Bug 222356] www/firefox: file-backed shared memory performance Message-ID: <bug-222356-21738@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=222356 Bug ID: 222356 Summary: www/firefox: file-backed shared memory performance Product: Ports & Packages Version: Latest Hardware: Any OS: Any Status: New Severity: Affects Only Me Priority: --- Component: Individual Port(s) Assignee: gecko@FreeBSD.org Reporter: tijl@FreeBSD.org CC: alc@FreeBSD.org, kib@FreeBSD.org Assignee: gecko@FreeBSD.org Flags: maintainer-feedback?(gecko@FreeBSD.org) Created attachment 186420 --> https://bugs.freebsd.org/bugzilla/attachment.cgi?id=186420&action=edit firefox patch Multi-process firefox appears to use a lot of shared memory backed by files on /tmp. If /tmp is not tmpfs but a regular file system this causes significant delays. Scrolling pages can be slow for example. This can be improved by patching firefox to use MAP_NOSYNC which prevents dirty pages being flushed to disc as long as they are mapped. When they are unmapped (and all descriptors have been closed) FreeBSD still flushes them though and there are several situations where firefox does this (e.g. switching between tabs and minimising and restoring the browser window). The backing files have been unlinked so why doesn't FreeBSD just discard the pages? I've attached a patch for firefox that works around this problem by using POSIX shared memory with shm_open for the case of anonymous shared memory. Named shared memory is left unchanged but doesn't appear to be used. The patch also removes recording of the inode because I don't think it's valid for shm_open. -- You are receiving this mail because: You are the assignee for the bug.
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