Re: mosbench revisited

On Wed, Aug 03, 2011 at 02:21:25PM -0400, Robert Haas wrote:
> It would be nice if the Linux guys would fix this problem for us, but
> I'm not sure whether they will.  For those who may be curious, the
> problem is in generic_file_llseek() in fs/read-write.c.  On a platform
> with 8-byte atomic reads, it seems like it ought to be very possible
> to read inode->i_size without taking a spinlock.

Interesting. There's this thread from 2003 suggesting the use of pread
instead, it was rejected on the argument that lseek is cheap so not a
problem.

http://archives.postgresql.org/pgsql-patches/2003-02/msg00197.php

Perhaps we now have a benchmark where the effect can be measured.

There's the issue about whether it screws up the readahead mechanism...

Have a nice day,
--
Martijn van Oosterhout   <kleptog@svana.org>   http://svana.org/kleptog/
> He who writes carelessly confesses thereby at the very outset that he does
> not attach much importance to his own thoughts.  -- Arthur Schopenhauer