Git migration: subdirs under packages/

[Paweł Sikora]

On Monday 25 of June 2012 18:52:32 Jan Rękorajski wrote:
> Small suggestion - add ability to slug.py to work with package(s)
> in a one level hash directories based on the first letter
> of package name, like this:
> 
> packages/[0-9A-Za-z]/<package dir>
> 
> Rationale: having entire packages checked out is RPITA, entering/listing
> packages/ directory is painfully slow - much slower than with CVS.
> One level hash will greatly speedup things.

this is a bad workaround. the core problem is in glibc's readdir()
which calls getdents syscall multiple times with small 32k buffer.
e.g, for rpm/packages, `ls -1` produces:

(...)
getdents(3, /* 913 entries */, 32768)   = 32760
getdents(3, /* 911 entries */, 32768)   = 32744
getdents(3, /* 914 entries */, 32768)   = 32736
getdents(3, /* 906 entries */, 32768)   = 32760
getdents(3, /* 919 entries */, 32768)   = 32752
getdents(3, /* 919 entries */, 32768)   = 32768
getdents(3, /* 917 entries */, 32768)   = 32744
getdents(3, /* 919 entries */, 32768)   = 32744
getdents(3, /* 917 entries */, 32768)   = 32744
getdents(3, /* 907 entries */, 32768)   = 32728
getdents(3, /* 915 entries */, 32768)   = 32736
getdents(3, /* 918 entries */, 32768)   = 32752
getdents(3, /* 918 entries */, 32768)   = 32744
getdents(3, /* 921 entries */, 32768)   = 32752
getdents(3, /* 907 entries */, 32768)   = 32752
getdents(3, /* 465 entries */, 32768)   = 16784
getdents(3, /* 0 entries */, 32768)     = 0
(...)