My pi 4 4gb is running at about 4 watts per my apc ups (I don’t have a more accurate way to measure). It only has HDMI turned off at the moment - on my next pi 4 I’ll be playing a little more with power settings.

The currently running pi 4 can be found here:
https://boinc.bakerlab.org/rosetta/show_host_detail.php?hostid=4215281

I also went ahead and setup a pi 3B+. Trying to run 4 processes, I ended up running out of memory and thrashing, even with zram - 3 processes seems to be working much better.

Newer versions of zram also an option for mem_limit, have a look here:
https://www.kernel.org/doc/html/latest/admin-guide/blockdev/zram.html
You could set it to 70-80% of RAM for example while also keeping the max size at 200%. This would enable utilizing the swap as well (although a kernel with zswap would be more ideal for this).

After you measure the overhead that deflate causes (is it kswapd?), you may try some other compression algorithm as well.

I'll soon have a look at whether I can patch out malloc via LD_PRELOAD to enable KSM. That could help a lot.

You may want to see whether setting /proc/sys/vm/page-cluster to 0 could help with the zram overhead.
https://www.kernel.org/doc/html/latest/admin-guide/sysctl/vm.html#page-cluster

i did that and committed 2 GB in there. it is somewhat a 'waste' of space on the SD card but i found it is actually useful.
there are quite a lot of tmpfs being mounted and perhaps some daemons running in the background at low priority.
i found that while boinc is running, the swap space is apparently used. i'd imagine that some of the tmpfs partitions are saved into swap instead.
that would actually free up some precious ram memory and allow r@h tasks to run

in terms of zram, i'm a little concerned that it may take more cpu 'effort' than simply swap

Its interesting. I have one RPi3B+ with 1Gigs of RAM and it crunched a lot of WUs but meanwhile R@H increased minimum RAM requirements from 850MB to ~1700MB and now it hasn't got WU-s.

I have also an OdroidC2 with 2Gis of RAM and it crunching fine with 2 WUs in parallel around 50°C.

BTW my RPI4B+ (4Gig of RAM) crunching only one WU at a time because of stock heatshink and it runs around 55-60°C.

Why does Ethernet go down when turning off USB? Can’t they be disabled independently?

This might sound like over doing it, but every watt counts in your rig efficiency and your temperatures.

I thought this would be a good place to ask. I want to set up a personal Raspberry Pi4 for myself and possibly my kids. Can anyone suggest a good setup to purchase that is reasonably priced but is well setup for running R@h?

Per this article, the pi’s wireless uses 10x the power of Ethernet, just being idle (unfortunately, it doesn’t provide WiFi load power usage).

Could you perhaps try a development version of BOINC to see if it has been fixed already? I see that the website binaries for PC have already been updated, but ARM seems to be lagging behind (maybe compile from source?). I could think of a quick workaround script that detects when a job is finishing and temporarily suspends all others while it is saving its files, but that would be a major hack. Or perhaps trying a faster SD card or faster file system might help (maybe not).

Are you positive that the task wouldn't start by itself even if you waited for a few minutes? Maybe the things are related: it is trying to start the next job while the previous is preparing its results? (Just guessing) Could you find anything in the logs (boinccmd --get_messages)? Boinc usually explains why it is or is not doing things.

131: 15-Apr-2020 20:06:36 (low) [Rosetta@home] Sending scheduler request: To fetch work.                                                                                                              
132: 15-Apr-2020 20:06:36 (low) [Rosetta@home] Requesting new tasks for CPU                                                                                                                           
133: 15-Apr-2020 20:06:38 (low) [Rosetta@home] Scheduler request completed: got 0 new tasks                                                                                                           
134: 15-Apr-2020 20:06:38 (low) [Rosetta@home] No tasks sent                                                                                                                                          
135: 15-Apr-2020 20:06:38 (user notification) [Rosetta@home] Message from server: Rosetta needs 1907.35 MB RAM but only 966.93 MB is available for use.                                               
136: 15-Apr-2020 20:11:44 (low) [Rosetta@home] project suspended by user                                                                                                                             
137: 15-Apr-2020 20:12:14 (low) [Rosetta@home] update requested by user                                                                                                                               
138: 15-Apr-2020 20:12:18 (low) [Rosetta@home] Sending scheduler request: Requested by user.                                                                                                          
139: 15-Apr-2020 20:12:18 (low) [Rosetta@home] Not requesting tasks: suspended via Manager                                                                                                            
140: 15-Apr-2020 20:12:20 (low) [Rosetta@home] Scheduler request completed                                                                                                                            
141: 15-Apr-2020 20:12:33 (low) [Rosetta@home] task rb_04_12_20719_20959_ab_t000__h001_robetta_IGNORE_THE_REST_07_07_911363_14_1 suspended by user                                                    
142: 15-Apr-2020 20:12:38 (low) [Rosetta@home] task rb_04_12_20719_20959_ab_t000__h001_robetta_IGNORE_THE_REST_07_07_911363_14_1 suspended by user                                                    
143: 15-Apr-2020 20:12:41 (low) [Rosetta@home] task rb_04_12_20719_20959_ab_t000__h001_robetta_IGNORE_THE_REST_04_05_911363_16_1 suspended by user                                                    
144: 15-Apr-2020 20:12:42 (low) [Rosetta@home] task rb_04_12_20719_20959_ab_t000__h001_robetta_IGNORE_THE_REST_08_05_911363_12_1 suspended by user                                                    
145: 15-Apr-2020 20:12:55 (low) [Rosetta@home] project resumed by user                                                                                                                                
146: 15-Apr-2020 20:13:04 (low) [Rosetta@home] update requested by user                                                                                                                               
147: 15-Apr-2020 20:13:07 (low) [Rosetta@home] Sending scheduler request: Requested by user.                                                                                                          
148: 15-Apr-2020 20:13:07 (low) [Rosetta@home] Not requesting tasks: some task is suspended via Manager                                                                                               
149: 15-Apr-2020 20:13:09 (low) [Rosetta@home] Scheduler request completed                                                                                                                            
150: 15-Apr-2020 20:14:03 (low) [Rosetta@home] task rb_04_12_20719_20959_ab_t000__h001_robetta_IGNORE_THE_REST_07_07_911363_14_1 resumed by user                                                      
151: 15-Apr-2020 20:15:04 (low) [Rosetta@home] task rb_04_12_20719_20959_ab_t000__h001_robetta_IGNORE_THE_REST_04_05_911363_16_1 resumed by user                                                      
152: 15-Apr-2020 20:15:29 (low) [Rosetta@home] task rb_04_12_20719_20959_ab_t000__h001_robetta_IGNORE_THE_REST_08_05_911363_12_1 resumed by user                                                      
153: 15-Apr-2020 20:16:31 (low) [Rosetta@home] Sending scheduler request: To fetch work.                                                                                                              
154: 15-Apr-2020 20:16:31 (low) [Rosetta@home] Requesting new tasks for CPU                                                                                                                           
155: 15-Apr-2020 20:16:34 (low) [Rosetta@home] Scheduler request completed: got 2 new tasks                                                                                                           
156: 15-Apr-2020 20:16:37 (low) [Rosetta@home] Started download of rb_04_15_21668_21257_ab_t000__robetta_FLAGS                                                                                        
157: 15-Apr-2020 20:16:37 (low) [Rosetta@home] Started download of rb_04_15_21668_21257_ab_t000__robetta.zip                                                                                          
158: 15-Apr-2020 20:16:39 (low) [Rosetta@home] Finished download of rb_04_15_21668_21257_ab_t000__robetta_FLAGS                                                                                       
159: 15-Apr-2020 20:16:39 (low) [Rosetta@home] Finished download of rb_04_15_21668_21257_ab_t000__robetta.zip                                                                                         
160: 15-Apr-2020 20:16:39 (low) [Rosetta@home] Started download of rb_04_15_21668_21257_ab_t000__robetta.200.3mers.index.gz                                                                           
161: 15-Apr-2020 20:16:39 (low) [Rosetta@home] Started download of rb_04_15_21668_21257_ab_t000__robetta.200.11mers.index.gz                                                                          
162: 15-Apr-2020 20:16:41 (low) [Rosetta@home] Finished download of rb_04_15_21668_21257_ab_t000__robetta.200.3mers.index.gz                                                                          
163: 15-Apr-2020 20:16:41 (low) [Rosetta@home] Finished download of rb_04_15_21668_21257_ab_t000__robetta.200.11mers.index.gz                                                                         
164: 15-Apr-2020 20:17:10 (low) [Rosetta@home] Starting task rb_04_15_21668_21257_ab_t000__robetta_IGNORE_THE_REST_03_11_916702_5_0                       

Also, could you perhaps post some stats while the Pi is fully loaded and happily crunching with BOINC? I would be interested in memory usage and compression ratio: `ps -e v` (or the relevant boinc lines of `top`), `free`, `cat /proc/swaps` and `zramctl` (or the appropriate folder in sysfs)

Seeing 8 boinc processes in your listing worries me. Maybe some of them got stuck? Anyway, could you perhaps share the results after completion (time, credits, decoy count, WS_MAX)?

Not sure how compressing RAM/Swap would work out for you, however it's pretty easy to set up the swap partition on an external drive, so you don't have to worry about SD card wear as much.

However, not all Boinc projects use a lot of RAM.
You could run 2 threads running Rosetta, and 2 running other project(s).

I recommend keeping at least 1 core free on the Pi. If you’ve got a 1GB Pi only run one at a time. If using zram you might be able to run two at a time. Why? zram needs some CPU time to do its job so keeping cores free means they are available without having to swap the task out.

When the tasks start they unzip over 1.5GB of data and copy files to the slot directory. That is a killer for the SD card. I believe the unzip part is multi-threaded so it will use all available cores but it still takes a few minutes to write to the SD card.

Thanks for sharing! I like your setup. Are you connecting over wifi? Could you perhaps measure the power draw? You may use either a kill-a-watt or the built-in power gauge inside your laptop if you connect to a high power charger port.
I'm interested in how low can we get in power? Can you underclock the CPU/GPU? Can you switch off the LEDs? Can we switch wifi on periodically only for transfers (from cron for example)?

3 Rosetta tasks in 1GB sounds like pushing the limit a bit, but we'll see how it performs. You may get some more space if you added a little bit more zram and if you select a better algorithm. Basically I would adjust the end of the script like this:

mem=$(( ($totalmem * 4 / 3 / $cores)* 1024 ))
modprobe deflate
modprobe zlib
modprobe lz4hc_compress
core=0
while [ $core -lt $cores ]; do
  echo deflate > /sys/block/zram$core/comp_algorithm ||
   echo zlib > /sys/block/zram$core/comp_algorithm ||
   echo lz4hc > /sys/block/zram$core/comp_algorithm ||
   echo lz4 > /sys/block/zram$core/comp_algorithm
# not sure which one this kernel has
  echo $mem > /sys/block/zram$core/disksize
  mkswap /dev/zram$core
  swapon --discard -p 5 /dev/zram$core # reclaim memory better
  let core=core+1
done

You may set the GPU memory as low as you like, because you can run a vncserver in a virtual framebuffer without a real X11. You may need to double check ~/.vnc/xstartup to execute an lxsession or at least a terminal. But why do you need X, if you can use boinccmd, boinctui or even remote RPC?