Skip to content
By using Twitter’s services you agree to our Cookies Use. We and our partners operate globally and use cookies, including for analytics, personalisation, and ads.

This is the legacy version of twitter.com. We will be shutting it down on June 1, 2020. Please switch to a supported browser, or disable the extension which masks your browser. You can see a list of supported browsers in our Help Center.

  • Home Home Home, current page.
  • About

Saved searches

  • Remove
  • In this conversation
    Verified accountProtected Tweets @
Suggested users
  • Verified accountProtected Tweets @
  • Verified accountProtected Tweets @
  • Language: English
    • Bahasa Indonesia
    • Bahasa Melayu
    • Català
    • Čeština
    • Dansk
    • Deutsch
    • English UK
    • Español
    • Filipino
    • Français
    • Hrvatski
    • Italiano
    • Magyar
    • Nederlands
    • Norsk
    • Polski
    • Português
    • Română
    • Slovenčina
    • Suomi
    • Svenska
    • Tiếng Việt
    • Türkçe
    • Ελληνικά
    • Български език
    • Русский
    • Српски
    • Українська мова
    • עִבְרִית
    • العربية
    • فارسی
    • मराठी
    • हिन्दी
    • বাংলা
    • ગુજરાતી
    • தமிழ்
    • ಕನ್ನಡ
    • ภาษาไทย
    • 한국어
    • 日本語
    • 简体中文
    • 繁體中文
  • Have an account? Log in
    Have an account?
    · Forgot password?

    New to Twitter?
    Sign up
pcwalton's profile
Patrick Walton
Patrick Walton
Patrick Walton
@pcwalton

Tweets

Patrick Walton

@pcwalton

Research engineer at Mozilla

San Francisco, CA
pcwalton.github.io
Joined November 2009

Tweets

  • © 2020 Twitter
  • About
  • Help Center
  • Terms
  • Privacy policy
  • Imprint
  • Cookies
  • Ads info
Dismiss
Previous
Next

Go to a person's profile

Saved searches

  • Remove
  • In this conversation
    Verified accountProtected Tweets @
Suggested users
  • Verified accountProtected Tweets @
  • Verified accountProtected Tweets @

Promote this Tweet

Block

  • Tweet with a location

    You can add location information to your Tweets, such as your city or precise location, from the web and via third-party applications. You always have the option to delete your Tweet location history. Learn more

    Your lists

    Create a new list


    Under 100 characters, optional

    Privacy

    Copy link to Tweet

    Embed this Tweet

    Embed this Video

    Add this Tweet to your website by copying the code below. Learn more

    Add this video to your website by copying the code below. Learn more

    Hmm, there was a problem reaching the server.

    By embedding Twitter content in your website or app, you are agreeing to the Twitter Developer Agreement and Developer Policy.

    Preview

    Why you're seeing this ad

    Log in to Twitter

    · Forgot password?
    Don't have an account? Sign up »

    Sign up for Twitter

    Not on Twitter? Sign up, tune into the things you care about, and get updates as they happen.

    Sign up
    Have an account? Log in »

    Two-way (sending and receiving) short codes:

    Country Code For customers of
    United States 40404 (any)
    Canada 21212 (any)
    United Kingdom 86444 Vodafone, Orange, 3, O2
    Brazil 40404 Nextel, TIM
    Haiti 40404 Digicel, Voila
    Ireland 51210 Vodafone, O2
    India 53000 Bharti Airtel, Videocon, Reliance
    Indonesia 89887 AXIS, 3, Telkomsel, Indosat, XL Axiata
    Italy 4880804 Wind
    3424486444 Vodafone
    » See SMS short codes for other countries

    Confirmation

     

    Welcome home!

    This timeline is where you’ll spend most of your time, getting instant updates about what matters to you.

    Tweets not working for you?

    Hover over the profile pic and click the Following button to unfollow any account.

    Say a lot with a little

    When you see a Tweet you love, tap the heart — it lets the person who wrote it know you shared the love.

    Spread the word

    The fastest way to share someone else’s Tweet with your followers is with a Retweet. Tap the icon to send it instantly.

    Join the conversation

    Add your thoughts about any Tweet with a Reply. Find a topic you’re passionate about, and jump right in.

    Learn the latest

    Get instant insight into what people are talking about now.

    Get more of what you love

    Follow more accounts to get instant updates about topics you care about.

    Find what's happening

    See the latest conversations about any topic instantly.

    Never miss a Moment

    Catch up instantly on the best stories happening as they unfold.

    Patrick Walton‏ @pcwalton 16 Dec 2019
    • Report Tweet
    • Report NetzDG Violation

    @johnregehr Found another tidbit about the PlayStation 3’s superoptimizer, if you’re interested https://news.ycombinator.com/item?id=21733922 … Doesn’t sound fun :(

    9:27 AM - 16 Dec 2019
    • 22 Likes
    • Dylan Chris Williams Andrew Gaspar StrangerSystems nick fitzgerald John Regehr John Ripley Nathan Sorenson
    5 replies 0 retweets 22 likes
      1. New conversation
      2. John Regehr‏ @johnregehr 16 Dec 2019
        • Report Tweet
        • Report NetzDG Violation
        Replying to @pcwalton

        yikes! one of my all-time favorite computer stories (which I tell here at every opportunity) was attending a talk by a Cell architect. super impressive perf numbers of course. someone in the audience asked how people were supposed to program it.

        1 reply 1 retweet 11 likes
      3. John Regehr‏ @johnregehr 16 Dec 2019
        • Report Tweet
        • Report NetzDG Violation
        Replying to @johnregehr @pcwalton

        he paused and said "any way you want"

        2 replies 0 retweets 23 likes
      4. 15 more replies
      1. New conversation
      2. Max Burke‏ @m18e 16 Dec 2019
        • Report Tweet
        • Report NetzDG Violation
        Replying to @pcwalton @johnregehr

        While the PS3's tools weren't too great at the beginning, they became *fantastic* as time progressed. The debugger is still my favorite of all time, the performance tools were great (IMO, preferable to PIX).

        1 reply 1 retweet 2 likes
      3. Patrick Walton‏ @pcwalton 16 Dec 2019
        • Report Tweet
        • Report NetzDG Violation
        Replying to @m18e @johnregehr

        Did you ever do the thing with the Cell superoptimizer where you submitted code at early hours of the morning so the servers wouldn’t be as loaded and it would have more time to run and would produce better code? That’s one of my favorite stories.

        1 reply 0 retweets 1 like
      4. 3 more replies
      1. New conversation
      2. Zach Wegner‏ @zwegner 16 Dec 2019
        • Report Tweet
        • Report NetzDG Violation
        Replying to @pcwalton @johnregehr

        Sounds like something we were doing in the twilight days of the Larrabee graphics team, ~2011: we made an exhaustive-search instruction scheduler that would run on a server farm to try and find the best schedule for critical basic blocks (like rasterizers)

        2 replies 0 retweets 2 likes
      3. Patrick Walton‏ @pcwalton 16 Dec 2019
        • Report Tweet
        • Report NetzDG Violation
        Replying to @zwegner @johnregehr

        Seems like there’s enough material here between the PS3 GPU and Larrabee for a short “survey of superoptimizers in practice” article. Would be really interesting.

        1 reply 0 retweets 1 like
      4. 1 more reply
      1. New conversation
      2. Geoff Langdale‏ @geofflangdale 16 Dec 2019
        • Report Tweet
        • Report NetzDG Violation
        Replying to @pcwalton @johnregehr

        I'm going to get a little salty at this idea that random search is "superoptimization". The whole point of someone inventing that silly word was to distinguish the bowdlerized "optimizers" (really improvers) from things that are going for actually optimal.

        3 replies 0 retweets 1 like
      3. Zach Wegner‏ @zwegner 16 Dec 2019
        • Report Tweet
        • Report NetzDG Violation
        Replying to @geofflangdale @pcwalton @johnregehr

        I always thought "superoptimizer" was kind of a misnomer already, since it's usually just "the shortest local inst. sequence", without even considering stuff like execution ports, etc. Adding more global effects like cache pressure/common input data makes "optimizing" hard

        4 replies 0 retweets 1 like
      4. 1 more reply
      1. New conversation
      2. Fabian Giesen‏ @rygorous 16 Dec 2019
        • Report Tweet
        • Report NetzDG Violation
        Replying to @pcwalton @johnregehr

        Yup, that's for the pixel shaders (vertex shaders were very different). One important thing to note is that RSX pixel shaders weren't really running shader code on shader cores in the way that modern GPUs do; it was more like the last hurrah of register combiners.

        1 reply 0 retweets 3 likes
      3. Fabian Giesen‏ @rygorous 16 Dec 2019
        • Report Tweet
        • Report NetzDG Violation
        Replying to @rygorous @pcwalton @johnregehr

        Or rather, a weird hybrid thing between those generations (it did have a proper register file for temps, not just a few slots). But RSX shaders ran in "passes". One pass = one arithmetic op (e.g. for tex coord generation), then one texture access, then arithmetic on the result.

        1 reply 0 retweets 0 likes
      4. 13 more replies

    Loading seems to be taking a while.

    Twitter may be over capacity or experiencing a momentary hiccup. Try again or visit Twitter Status for more information.

      Promoted Tweet

      false

      • © 2020 Twitter
      • About
      • Help Center
      • Terms
      • Privacy policy
      • Imprint
      • Cookies
      • Ads info