2008/11/11 André Warnier <aw@xxxxxxxxxx>: > dave selby wrote: > [...] >> >> OK ... I did not realize that there would be competition, the CPU load >> is not 100% so I don't understand why apache and firefox would be >> competing ? >> > It is a bit difficult to tell what is really happening, which is why it may > be better trying to isolate the different aspects and really finding out who > is using which resources for what. > > Now I'm really guessing, which is the best that can be done for now. > > You browser is getting a 28 Kbyte image from the server 5 times per second. > The server has to get this data, which means disk I/O, which also means CPU > time. > The browser is probably doing something with that data, if only updating its > cache maybe. More disk I/O. So you may have one or the other process > waiting for a chance to use the (same) disk, and spending CPU time on that. > If the browser is displaying the images, it needs memory to do so. There > may be other processes involved too (I see at least two other processes > which in your second "top", are also using considerably more CPU than in the > first one). If the total memory needed by your browser, plus all the other > apps including Apache, exceeds the physical memory available, there will be > memory swapping going on. That also costs CPU time, and extra I/O activity > that itself needs more CPU time to handle it. > And all these things, the way you are running them, are very inter-dependent > and happen at the same time : it is precisely when your browser is having to > work hardest to get the images, that your Apache also has to work harder, to > deliver them. Since you have a single CPU, it means that there will have to > be many more context switches from your Apache process to your browser > process, and so on. > See what I mean ? No wonder you get an exponential behaviour. > > The type of Apache you are using may also be playing a role. It looks as if > it is a threaded version, which maybe in this particular case also has a > particularly adverse behaviour. Many thanks for taking the time to explain this to me, I really appreciate you taking the time to make this clear. I will split the server / browser onto 2 x machines and post back the results Thanks once again Dave > > > --------------------------------------------------------------------- > The official User-To-User support forum of the Apache HTTP Server Project. > See <URL:http://httpd.apache.org/userslist.html> for more info. > To unsubscribe, e-mail: users-unsubscribe@xxxxxxxxxxxxxxxx > " from the digest: users-digest-unsubscribe@xxxxxxxxxxxxxxxx > For additional commands, e-mail: users-help@xxxxxxxxxxxxxxxx > > -- Please avoid sending me Word or PowerPoint attachments. See http://www.gnu.org/philosophy/no-word-attachments.html --------------------------------------------------------------------- The official User-To-User support forum of the Apache HTTP Server Project. See <URL:http://httpd.apache.org/userslist.html> for more info. To unsubscribe, e-mail: users-unsubscribe@xxxxxxxxxxxxxxxx " from the digest: users-digest-unsubscribe@xxxxxxxxxxxxxxxx For additional commands, e-mail: users-help@xxxxxxxxxxxxxxxx
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