On Sat, Mar 16, 2019 at 5:01 AM Dan Sommers <2QdxY4RzWzUUiLuE@potatochowder.com> wrote:
My situation is similar to Darren's: My primary connection to the internet is through my cell phone carrier and a mobile WiFi hot spot. In urban areas, I can get as much as 50 megabits per second, but presently, due to my remote location, it's around 5 or 6. I also have a monthly data cap, which I share with my wife, and only WiFi (i.e., no wires; that nice 300 megabits from hot spot to device is shared by all devices, and there's a per device limit, too). FWIW, I have an i7-7700HQ CPU.
In the old days (when large files were a megabyte or two and network bandwidth was measured in kilibits per second), we assumed that the network was the bottleneck. I think what Adam is propsing is that things are different now, and that the CPU is the bottleneck. As always, it depends. :-)
My vote, whether it has any weight or not, is for higher compression ratios at the expense of CPU cycles when decompressing; i.e., xz rather than zstd. Also, consider that the 10% increase in archive size is suffered repeatedly as servers store and propagate new releases, but that the increase in decompression time is only suffered by the end user once, likely during a manual update operation or an automated background process, where it doesn't matter much.
I used to have this argument with coworkers over build times and wake-from-sleep times. Is the extra time to decompress archives really killing anyone's productivity? Are users choosing OS distros based on how long it takes do install Open Office? Are Darren and I dinosaurs, doomed to live in a world where everyone else has a multi-gigabit per second internet connection and a cell phone class CPU?
Jokingly, but not as much as you think, Dan
I think you're overstating your case a little bit. In the United States, nothing less than 25 Mbps can legally be called broadband, and the average download speed is approaching 100 Mbps (90% of us have access to 25 Mbps or better internet). Zstd -19 is faster overall than xz -6 starting at around 20 Mbps, so it's a better choice even on some sub-broadband connections. Your PassMark score is only about 50% better than that used on the Squash compression test, so I don't know that the computer speed element is significant. Furthermore, if space saving is the primary concern, why are we using the default xz -6 option, rather than something stronger like -9? I support using zstd because even in the absolute worst case (instant decompression), you're looking at less than a 10% increase in upgrade time, while for most users, a reduction of 50% would not be atypical (lzma is slow!). I'm not suggesting throwing out all concerns about disk space and transfer time, I'm just suggesting that times have changed *somewhat*, and that for most users zstd may provide a better trafe-off. In my case (100 Mbit connection), which is close to the US average, downloading and decompressing the latest Firefox package would take less than 1/3 the time it currently takes if we switched to zstd. Adam