On Fri, March 3, 2006 1:09 pm, Nick Rout wrote: > I have a machine that is a pIII 400 MHz with 64M RAM. > > It is not doing much other than running torrentflux, a web based > frontend to the bittornado bittorrent client, which also involves mysql > and apache. > > a lot of the time it ticks along at a load average of 0.2-0.5. However > sometimes it shoots up to 5, 10, even more, for a while and after a > while shrinks back down to the stable level. During this time it becomes > pretty unresponsive. It is annoying me. > > When the LA is high top also shows that the machine is spending a lot of > time in the "wait" state. I assume this is an IO related problem, > probably disk related. swap is also in use most of the time. DMA is on, > but i don't know how well that is handled by the relatively old chipset > in the box. top doesn't show any processes using inordinate cpu time or > even memory (although swap is clearly in use). > > Is this "wait" state and high LA related to lack of ram and constant > swapping? the disk doesn't sound like its thrashing, but its hard to > tell when its not the only computer in the room. > > Or should I look elsewhere? Is the IO problem related to network issues > with a lot of connections on the go? (bittorrent is like that!) > > > -- > Nick Rout <[EMAIL PROTECTED]> > > wait = waiting on IO. It doesn't matter that 99% of the system memory is in use - that just shows that the OS is making the best use of it. But when any apperciable amount of swap is in use... that tends to be bad news. A small amount is ok, as the text segments of running programs tend to get mirrored there ( old versions of HP-UX were famous for the amount of time it took to start a program due to making this copy ), to improve the speed that a program can be swapped out, but with databases they tend to like to have large amounts of data in memory as well. With mysql it may be possible to limit this by setting lower values for the query cache ( query_cache_limit and query_cache_size ), the sort_buffer, join_buffer_size, and a few more I cant think of at the minute.
When in top, type M. This shows the the processes using the most memory. I expect mysql will be there. The RSS column shows how much is resident ( no, I know it doesn't really, but let's not get sidetracked here ). If the total is over 64MB, then you're in trouble at this point. Once swapping starts, performance plummets as does it's responsiveness. I expect that a massive injection of memory ( an extra 64MB? ) should improve things considerably. My $0.02, Steve -- Let us have a moment of silence for all Americans who are now stuck in traffic on their way to a health club to ride a stationary bicycle. - Congressman Earl Blumenauer (Oregon)
