On 5/25/2010 11:44 AM, David Brodbeck wrote:
>
> On May 24, 2010, at 2:05 PM, Les Mikesell wrote:
>
>> On 5/24/2010 3:51 PM, David Brodbeck wrote:
>>>
>>> On May 21, 2010, at 8:23 AM, Hyrum K. Wright wrote:
>>>> Actually, Subversion is a bit more intelligent about it, attempting to use modification times and sizes, before doing a byte-by-byte comparison.
>>>
>>> Even that can be slow if there are lots of files involved. Note that some filesystems have particularly bad performance if there are lots of files in a single directory, as well. This is especially true of NFS. In one extreme example, I've seen a simple "ls" take tens of minutes to produce any output in an NFS-mounted directory with ~1,000,000 files.
>>
>> But to be fair, note that ls sorts its output, so it can't output anything until it has read everything.
>
> True, but other operations were slow, too. The way readdir() works means that a lot of file operations inevitably involve a linear search of the directory.
And worse, creating a new file involves doing that search first to see
if it is new, then finding a free slot or growing the directory and
adding it all as an atomic operation, blocking any other process trying
to do the same. But, that's why subdirectories were invented - you don't
have to put everything on one big inefficient space.
--
Les Mikesell
lesmikesell_at_gmail.com
Received on 2010-05-25 19:00:19 CEST