Re: [PATCH setup] Add new option '--compact-os'

[Corinna Vinschen <corinna-cygwin@cygwin.com>]

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