>> I think I recall that lseek may have a negative effect on some OS's
>> readahead calculations (probably only systems that cannot handle an
>> lseek to the next page eighter) ? Do you think we should cache the
>> last value to avoid the syscall ?
>
> We really can't, since the point of doing it is to find out whether any
> other backends have extended the file since we last looked. Also, IIRC
Well yes. The value would need to be kept ajour by the backends that
extend, with an interlocked increment. We would thus need to keep the
count in shmem.
Andreas