Comment #13 on issue 6356 by albertod.zgz: TCP receive/send windows are too small (32KB) causing slower transfers http://code.google.com/p/chromium/issues/detail?id=6356
I disagree :) I just re-tested everything. Method was to use Wireshark to log TCP packets locally. For additional verification, I used an online checker ( http://www.speedguide.net/analyzer.php ) which sniffs incoming TCP packets and tells you their parameters, including TCP window size. These tests were conducted with the build at http://build.chromium.org/buildbot/snapshots/chromium-rel-xp/10983/ Scenario 1 - XP SP2 IE/Firefox: 17520 bytes Chrome: 32768 bytes Scenario 2 - XP SP2 + registry change (TCPWindowSize = 256000) IE/Firefox: 256960 bytes Chrome: 32768 bytes Scenario 3 - Vista SP1 IE/Firefox: Variable (5840-256960) Chrome: 32768 Some explanations: both XP and vista round to the next multiple of MSS (in my case 1460) for maximum efficiency, hence 256960 when requested 256000, unless overridden (32768 is suboptimal for this). On Vista, due to autotunning, the initial window starts small (sometimes it's 8760 or even 5840) but quickly grows to an optimal size (in my case, up to 256960) during transfers. In the case of Chrome, it stays fixed at 32768 no matter what. In practice, this limits speed just as expected. This is a table of download speed tests that I registered (under scenario 3, with a connection limit of about 600KB/s): PING (ms) CHROME SPEED FIREFOX SPEED 44-56 589 591 87-92 346 590 172-179 182 579 You might need to choose a server that is far away to see the effect (USA<->Europe should give about 150ms). The maximum speed Chrome will ever get is 32*(1/ping), where ping is the RTT in seconds. -- You received this message because you are listed in the owner or CC fields of this issue, or because you starred this issue. You may adjust your issue notification preferences at: http://code.google.com/hosting/settings --~--~---------~--~----~------------~-------~--~----~ Automated mail from issue updates at http://crbug.com/ Subscription options: http://groups.google.com/group/chromium-bugs -~----------~----~----~----~------~----~------~--~---
