Re: Making fsfs generate unique transaction names

[Blair Zajac]
> We're seeing around 10 commits per second, getting up to 20 commits
> per second during busy parts of the day. So I'm concerned about
> sharing the write lock for the commit process and just incrementing a
> transaction sequence.
>
> I don't know how fast getting a lock, incrementing the counter and
> releasing it will be, nor how much contention.

On my 1.8 GHz Athlon, I can do this:

  open
  fcntl(F_WRLCK)
  read
  atoi
  lseek
  write(n+1)
  close [note that this unlocks the file]
  return n

around 70000 times per second. Thus, if I wanted to do it 20 times per
second, I wouldn't worry much about either efficiency or contention.

-- 
Peter Samuelson | org-tld!p12n!peter | http://p12n.org/