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Re: HTTP 2.0 performance is slower than HTTP 1.1 in libcurl

From: Tatsuhiro Tsujikawa <>
Date: Mon, 23 May 2016 21:22:45 +0900


On Mon, May 23, 2016 at 6:21 PM, Daniel Stenberg <> wrote:

> On Mon, 23 May 2016, Rajiullah Shammi wrote:
> Just to inform, by shrinking the H2_BUFSIZE to 16K, I haven’t seen any
>> improvement in my test (
> Ah, yeah I was sort of suspecting that it wouldn't make anything better
> when using many streams. What if you make it much larger, does that change
> anythinh?
> And for reference, I'm attaching my *experimental* patch to set the
> initial window size to 512MB and disable nghttp2's automatic window
> handling.

In my opinion, I recommend to keep using nghttp2's auto WINDOW_UPDATE
feature while enlarging window size to 512MiB unless you'd want to
implement custom WINDOW_UPDATE scheduler. With large WINDOW_SIZE, nghttp2
will send WINDOW_UPDATE less frequently (current implementation, it sends
WINDOW_UPDATE when it receives 256MiB without sending any WINDOW_UPDATE).

Bumping up window size of connection should be done in initialization
phase, e.g., after nghttp2_submit_settings in http2_switched.

Best regards,
Tatsuhiro Tsujikawa

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Received on 2016-05-23