[Make-wifi-fast] QCut - "Understanding on-device bufferbloat for cellular upload", Guo et al

Rich Brown richb.hanover at gmail.com
Tue Nov 15 12:00:29 EST 2016

Google Alerts sent a link to this paper: "Understanding on-device bufferbloat for cellular upload" available at: http://dl.acm.org/citation.cfm?id=2987490 (ACM Paywall...)

In my two-minute skim of the paper, I see they describe how latency gets bad on cellular devices (no kidding) and then propose QCut, a queue inserted between the qdisc and the hardware. They say:

... QCut operates in the kernel space and takes as input only information of buffer occupancy and transmission statistics, which is exposed by most cellular radio firmware from Qualcomm and likely other vendors.

Since directly limiting the firmware buffer occupancy is difficult, QCut controls the firmware queuing delay indirectly in the kernel by controlling how fast packets from Qdisc flow into the firmware buffer. QCUT estimates the radio firmware buffer occupancy and queuing delay to decide the transmission of packets to the firmware dynamically...

Their analysis and charts show that QCut helps a lot.

I found it interesting that they make measurements with both weak and strong signal strength, to indicate the hits that are caused by differing signal strength.



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