Urs Holzle from google on “Speed Matters”

From Urs’ talk at the velocity2010 conference [ More info : Google, datacenterknowledge ]

  • Average web page - 320kb, 44 resources, 7 dns lookups, doesn’t compress 3rd of its content
  • Aiming for 100ms page load times for chrome
  • Chrome: HTML5, V8 JS engine, DNS prefetching, VP8 codec, opensource, spurs competition
  • TCP improvements
    • Fast start (higher initial congestion window)
    • Quick loss recovery (lower retransmit timeouts)
    • Makes Google products 12% faster
    • No handshake delay (app payload in SYN packets)  [ Didn’t know this was possible !!! ]
  • DNS improvements
    • Propagate client IP in DNS requests (to allow servers to better map users to the closest servers)
  • SSL improvements
    • False start (reduce 1 round trip from handshake)
      • 10% faster (for Android implementation)
    • Snap start (zero round trip handshakes, resumes)
    • OCSP stapling (avoid inline roundtrips)
  • HTTP improvements (SPDY):
    • Header compression
    • Stream multiplexing and prioritization
    • Server push/hints
    • 25% faster
  • Test done
    • Download the same “top 25” pages via HTTP and SPDY, network simulates a 2Mbps DSL link, 0% packet loss - Number of packets dropped by 40%
    • On low bandwidth links, headers are surprisingly costly. Can add 1 second of latency.
  • Public DNS:
    • reduces recursive resolve time by continuously refreshing cache
    • Increases availability through adequate provisioning
  • Broadband pilot testing going on
    • Fix the “last mile” complaint
    • Huge increase of 100x
  • More developer tools by Google
    • Page speed, speed tracer, closure compiler, Auto spriter
  • More awareness about performance


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