[PATCH setup] Add new option '--compact-os'
Corinna Vinschen
corinna-cygwin@cygwin.com
Mon May 17 10:17:15 GMT 2021
On May 13 16:42, Christian Franke wrote:
> Corinna Vinschen via Cygwin-apps wrote:
> > When running a shell script, certain executables (especially coreutils,
> > gawk, sed, grep, find) are not so very infrequently accessed. Is this
> > compression really feasible for these binaries? Did you compare shell
> > script performance with non-compressed, XPRESS16K and LZX compressed
> > /bin dir?
>
> Good point. Now I did a test with a ./configure script run after reboot:
> There was significant difference with /bin/*.exe (only) uncompressed, NTFS-,
> XPRESS16K- or LZX-compressed. Time was always around 23s.
>
> Here a read speed test with fast and slow storage and a 10+ years old
> i7-2600K (4C/8T). The 256MiB test file was generated by concatenating
> various EXE files. All file accesses were the first after reboot. AV
> (defender) was turned off:
>
>
> Compression MiB T1 T2 T3,T4
> ======================================
> None 256 0.69s 10.1s <0.02s
> NTFS 159 1.03s 8.1s <0.02s
> XPRESS4K 138 -
> XPRESS8K 128 -
> XPRESS16K 123 0.64s 5.4s <0.02s
> LZX 97 0.79s 4.8s <0.02s
>
> T1,T2: Read whole file: time dd if=FILE bs=FILESIZE of=/dev/null
> T3,T4: Read last byte: time dd if=FILE bs=1 skip=FILESIZE-1 of=/dev/null
>
> T1,T3: SATA SSD, raw read speed with dd bs=1M: ~520MB/s
> T2,T4: USB3 flash drive via USB2, raw read speed: ~27MB/s
>
>
> As expected, compression helps to improve 'virtual' read speed on slow
> storage. Otherwise, it depends on storage speed, CPU speed, system load, ...
> As unexpected (for me), even LZX seems to be suitable for random reads which
> are done when EXE files are preloaded or paged-in.
>
> If the files were already cached, all read times were similar: ~0.135s for
> the whole file.
>
> For more flexibility, I will provide a new version of the patch with
> '--compact-os ALGORITHM' option.
Great, thanks!
Corinna
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