Messages in this thread | | | Date | Mon, 29 Dec 2003 17:58:44 -0500 (EST) | From | Thomas Molina <> | Subject | Re: 2.6.0 performance problems |
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On Mon, 29 Dec 2003, Linus Torvalds wrote:
> > > On Mon, 29 Dec 2003, Thomas Molina wrote: > > > > I just finished a couple of comparisons between 2.4 and 2.6 which seem to > > confirm my impressions. I understand that the comparison may not be > > apples to apples and my methods of testing may not be rigorous, but here > > it is. In contrast to some recent discussions on this list, this test is > > a "real world" test at which 2.6 comes off much worse than 2.4. > > Are you sure you have DMA enabled on your laptop disk? Your 2.6.x system > times are very high - much bigger than the user times. That sounds like > PIO to me.
It certainly looks like DMA is enabled. Under 2.4 I get:
[root@lap root]# hdparm /dev/hda
/dev/hda: multcount = 16 (on) IO_support = 1 (32-bit) unmaskirq = 1 (on) using_dma = 1 (on) keepsettings = 0 (off) readonly = 0 (off) readahead = 8 (on) geometry = 2584/240/63, sectors = 39070080, start = 0
Under 2.6 I get:
[root@lap root]# hdparm /dev/hda
/dev/hda: multcount = 16 (on) IO_support = 1 (32-bit) unmaskirq = 1 (on) using_dma = 1 (on) keepsettings = 0 (off) readonly = 0 (off) readahead = 256 (on) geometry = 38760/16/63, sectors = 39070080, start = 0
Relevant items from my 2.6 configuration file:
CONFIG_GENERIC_ISA_DMA=y CONFIG_BLK_DEV_IDEDMA_PCI=y # CONFIG_BLK_DEV_IDEDMA_FORCED is not set CONFIG_IDEDMA_PCI_AUTO=y # CONFIG_IDEDMA_ONLYDISK is not set # CONFIG_IDEDMA_PCI_WIP is not set CONFIG_BLK_DEV_ADMA=y CONFIG_BLK_DEV_IDEDMA=y # CONFIG_IDEDMA_IVB is not set CONFIG_IDEDMA_AUTO=y # CONFIG_DMA_NONPCI is not set
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