Messages in this thread | | | Date | Fri, 02 Mar 2001 20:44:56 -0500 | From | Jeremy Jackson <> | Subject | Re: [Re: paging behavior in Linux] |
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Manfred Spraul wrote:
> Neelam Saboo wrote: > > > > hi, > > > > After I installed a newer version of Kernel (2.4.2) and enable DMA option in
Ah hah! There's a huge difference in performance (in my experience) with DMA. also, using hdparm utility, *most* drives work fine with dma, irq unmasking, multisector transfers, and 32bit access. hdparm -i /dev/hda or such will tell you maximum multisector supported. the only reason these aren't enabled AFAIK is that SOME drives don't, and when there's a problem it could cause data loss.
The worker thread may just have been overtaking the prefetcher because dma was off and disk was slow.
> > > hardware configuration, the behavior changes. > > I can see performance improvements when another thread is used. Also, i can > > see timing overlaps between two threads. i.e. when one thread is blocked on a > > page fault, other thread keeps working. > > Now, how can this behavior be explained , given the earlier argument. > > Is it that, a newer version of kernel has fixed the problem of the semaphore > > ? > > > No, that change won't happen until 2.5 > > I can only guess: > the other thread keeps working until it causes a page fault - with both > 2.4.1 and 2.4.2. > > I haven't followed the threads about the mm changes closely, but I > assume that the swapout behaviour changed, and that your worker thread > now runs without causing page faults.
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