On Thu, 2006-06-15 at 17:50 +0800, Qingqing Zhou wrote: > "Simon Riggs" <[EMAIL PROTECTED]> wrote > > > > Can we do the same for the file descriptors in fd.c? > > > > Very often the total number of file descriptors is much less than the > > maximum, so it would make sense to only maintain the LRU when we are > > using more than 50%-75% of the maximum. > > > > I am not against doing it but AFAIR the LRU file operations is
> (1) not frequent; The LRU moves each time we do FileRead or FileWrite, not just on open/close operations. > (2) the cost is only several CPU circles if we do not run out of > fds; So its not really likely ever to show high on oprofile, but if its an avoidable operation that isn't always needed, why do it? > (3) the LRU lseek/close/open big cost is still not avoidable when we > really run out of fds. Agreed, but the limit is reasonably high, so this isn't anywhere near being something we always hit otherwise we would be more worried. -- Simon Riggs EnterpriseDB http://www.enterprisedb.com ---------------------------(end of broadcast)--------------------------- TIP 9: In versions below 8.0, the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match
