Fastest Sort. Sort Faster, Max Speed

alias sortfast='sort -S$(($(sed '\''/MemF/!d;s/[^0-9]*//g'\'' /proc/meminfo)/2048)) $([ `nproc` -gt 1 ]&&echo -n --parallel=`nproc`)'
sort is way slow by default. This tells sort to use a buffer equal to half of the available free memory. It also will use multiple process for the sort equal to the number of cpus on your machine (if greater than 1). For me, it is magnitudes faster. If you put this in your bash_profile or startup file, it will be set correctly when bash is started. sort -S1 --parallel=2 <(echo) &>/dev/null && alias sortfast='sort -S$(($(sed '\''/MemF/!d;s/[^0-9]*//g'\'' /proc/meminfo)/2048)) $([ `nproc` -gt 1 ]&&echo -n --parallel=`nproc`)' Alternative echo|sort -S10M --parallel=2 &>/dev/null && alias sortfast="command sort -S$(($(sed '/MemT/!d;s/[^0-9]*//g' /proc/meminfo)/1024-200)) --parallel=$(($(command grep -c ^proc /proc/cpuinfo)*2))"
Sample Output
89/490MB        4.22 2.03 1.01 2/85 7081
[24309:24308 0:4220] 08:01:28 Mon Feb 27 [root@galileo:pts/2 +1] ~
$ sort -S400M -u -i -f --parallel=4 files.nocombined.sorted | pv > ~/files.nocombined.reallysorted                                                                                                                                                                                                                              
9.95MB 0:01:39 [ 103kB/s] [     <=>             

What Others Think

Using so much mem is dangerous. Also using more processes than CPUs suggests you're waiting on disk. It would help if you mentioned your input source medium, TMPDIR medium and output medium. Note also the recent nproc command which might be handier than grepping cpuinfo Note also this might be a safer mem usage estimate: free -m | awk '$4 && $7 {print $4+$7-200}'
pixelbeat · 552 weeks ago
Thanks for that nproc command and I like the way your command includes the cache... Also good mention of the TMPDIR medium and output medium since these are heavily used. My tmpdir is either tmpfs (memory) or on a high-performance 6-disk raid 0 array.. both max out at 5GB size-wise. I use a custom TMPDIR so didn't include that, but really will make a huge difference if setup correctly. This has 8 subprocesses and 302 calls strace -c sh -c "free -m | awk '\$4 && \$7 {print \$4+\$7-200}'" This has 297 calls and 8 subproccesses strace -c sh -c "free -m|sed '1d;s/^.*: *[0-9]* *[0-9]* *//;s/ [ 0-9]*$//;q'" This has no subprocesses and only 192 calls strace -c sh -c 'sed -n "/mF/s/^.*: *\([0-9]\+\) kB$/\1/p" /proc/meminfo' I will update the above with the changes made per your suggestions.
AskApache · 549 weeks and 3 days ago
Ok there you go.. what do you think of that? Any other ideas?
AskApache · 549 weeks and 3 days ago

What do you think?

Any thoughts on this command? Does it work on your machine? Can you do the same thing with only 14 characters?

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