On Tue, Dec 11, 2001 at 02:53:41AM +0100, Florian Lohoff wrote: > On Mon, Dec 10, 2001 at 09:07:57PM +0100, Florian Lohoff wrote: > > Hi, > > the attached patch fixes part of the DMA problems we see with multiple > > disks and the sgiwd93.c with DISCONNECTs. Klaus patch formerly just > > disabled all DMA replacing it with PIO which is a major performance hit. > > > > This patch simply deletes all the HPC Scatter/Gather stuff thus we will > > see a couple more interrupts due to all segments beeing transferred > > individually. The transfer itself still happens with the HPC DMA thus > > the performance impact will not be that large. I am running a test right > > now but it seems the error is gone. > > Ok - I am running the attached script right now which copies a kernel > source tree from one disk to another disk in a loop. I ran this on the a > 133Mhz R4600 Indy with 2 SCSI Disks on the same SCSI bus. Without the > patch not a single cycle in this script made it through as on page in > the binarys would be corrupted. Also a whole bunch of files of the source > tree would be broken, mangled truncated - Whatever might happen. Nothing > of this now happened while running the test for the last 5 hours. The > machine is still up and running and kind of responsive. > > I am unsure if we should put this into CVS as it brings us correctness > for the price of some performance penalty. Can you very roughly estimate the performance hit - let's say the slow down when copying the whole kernel-tree once? -- Guido
