{"id":9,"date":"2011-08-26T16:14:10","date_gmt":"2011-08-26T16:14:10","guid":{"rendered":"http:\/\/blog.mozilla.org\/nfroyd\/?p=9"},"modified":"2011-08-26T16:14:10","modified_gmt":"2011-08-26T16:14:10","slug":"making-firefox-work-with-syzygy","status":"publish","type":"post","link":"https:\/\/blog.mozilla.org\/nfroyd\/2011\/08\/26\/making-firefox-work-with-syzygy\/","title":{"rendered":"making firefox work with syzygy"},"content":{"rendered":"

The good folks at Google have written a clever tool called Syzygy, which is part of the Sawbuck project<\/a>.\u00a0 The best summary of Syzygy comes from its design document<\/a>:<\/p>\n

Syzygy is a suite of tools to perform profile-guided, function-level reordering of 32-bit Windows PE executables, to optimize their layout improved performance, notably for improved paging patterns.<\/p><\/blockquote>\n

Google wrote Syzygy for use with Chrome, but the tool is equally applicable to any large application where you want to improve performance…like Firefox.\u00a0 In this case, we’re concerned with improving the layout of libxul, as that’s where the bulk of the Firefox code lives.\u00a0 Working with Syzygy involves four major steps:<\/p>\n

    \n
  1. Instrumenting the application binary in question;<\/li>\n
  2. Running the application to collect profile data (function addresses along with invocation time);<\/li>\n
  3. Passing the profile data through an ordering generator, which comes up with the order in which functions should be laid out in the optimized binary; and finally<\/li>\n
  4. Relinking the application binary using the ordering from step 3.<\/li>\n<\/ol>\n

    Step 1 is pretty easy; Firefox just needs to be compiled with Visual Studio’s \/PROFILE switch<\/a> to ensure that the instrumenter has all the information it needs.\u00a0 Steps 3 and 4 are likewise straightforward.<\/p>\n

    Step 2 appears to be the tricky part.\u00a0 Being good–lazy–computer programmers, the Google folks wrote a number of scripts and programs to automate this process, as well as some benchmarking infrastructure.\u00a0 However, the scripts are written with Chrome in mind; many places have Chrome-specific bits hardcoded.\u00a0 This is, of course, totally understandable, but it makes using those scripts with other programs difficult.<\/p>\n

    Over the past couple of weeks, I’ve been working at making Syzygy cooperate with Firefox.\u00a0 If you’re interested, you can see the modifications I’ve made in my sawbuck github project<\/a>.\u00a0 Things are working well enough that I can now run:<\/p>\n

    \n
    Debug\/py\/Scripts\/benchmark --user-data-dir flobbity --no-preload --no-prefetch ~\/ff-build\/dist\/bin\/firefox.exe<\/pre>\n<\/blockquote>\n
    (The --no-{preload,prefetch}<\/tt> options are required to work around Chrome-specific code that didn’t seem worth ripping out; the --user-data-dir<\/tt> specifies what profile to use when launching Firefox.)\u00a0 After waiting for a minute or two, the benchmark script reports:<\/p>\n
    \n
    RESULT firefox.exe: SoftPageFaults= [23495, 32139, 23356, 23343, 23299, 23167, 23063, 23141, 23113, 23267]\r\nRESULT firefox.exe: HardPageFaults= [1158, 10, 3, 3, 4, 2, 2, 2, 3, 2]<\/pre>\n<\/blockquote>\n
    This is for an unoptimized binary, of course.\u00a0 You can clearly see the OS’s page cache at work in runs after the first.<\/p>\n
    The scripts are not quite perfect yet.\u00a0 In particular, the call traces necessary to perform reordering don’t seem to be generated, for some peculiar reason that I haven’t ferreted out.\u00a0 Also, the script will indiscriminately kill any Mozilla-related apps running along with the Firefox instances being benchmarked; I couldn’t find any good way to limit the killing to windows associated with a particular profile.\u00a0 (IIUC the Chrome code correctly, it sets the window text of a hidden window to the full path to the profile directory in use.)\u00a0 But a good bit seems to work; hopefully progress will come faster now that the groundwork has been laid.<\/p>\n","protected":false},"excerpt":{"rendered":"
    The good folks at Google have written a clever tool called Syzygy, which is part of the Sawbuck project.\u00a0 The best summary of Syzygy comes from its design document: Syzygy is a suite of tools to perform profile-guided, function-level reordering of 32-bit Windows PE executables, to optimize their layout improved performance, notably for improved paging […]<\/p>\n","protected":false},"author":320,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"_links":{"self":[{"href":"https:\/\/blog.mozilla.org\/nfroyd\/wp-json\/wp\/v2\/posts\/9"}],"collection":[{"href":"https:\/\/blog.mozilla.org\/nfroyd\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.mozilla.org\/nfroyd\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.mozilla.org\/nfroyd\/wp-json\/wp\/v2\/users\/320"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.mozilla.org\/nfroyd\/wp-json\/wp\/v2\/comments?post=9"}],"version-history":[{"count":0,"href":"https:\/\/blog.mozilla.org\/nfroyd\/wp-json\/wp\/v2\/posts\/9\/revisions"}],"wp:attachment":[{"href":"https:\/\/blog.mozilla.org\/nfroyd\/wp-json\/wp\/v2\/media?parent=9"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.mozilla.org\/nfroyd\/wp-json\/wp\/v2\/categories?post=9"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.mozilla.org\/nfroyd\/wp-json\/wp\/v2\/tags?post=9"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}