I've run into a problem with running an nfsv4 server on a Marvell Kirkwood (armv5tel) platform. When copying a large file (>1GB) to the NFS server, thewrite speed will suddenly slow down to ~750kB/s and the CPU wait will jump to 100% for the remainder of the transfer. Other important points: * it doesn't happen on nfsv3 or any other protocol or indeed any other I/O that I have tried. * other I/O works fine on the server while this is happening. * the next operation will work normally unless it runs into the same problem again after starting out ok. * the server is running Debian testing (ARM) and kernel 2.6.39. I've tried 2.6.38 and 2.6.32 and they have the same problem. * I'm using gss/krb5i for the mounts * it doesn't seem to affect x86_64 servers running the same kernel version and distribution. Here is what vmstat 1 shows just as the problem occurs: procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu---- r b swpd free buff cache si so bi bo in cs us sy id wa 0 0 0 2828 44044 169100 0 0 0 35924 2931 2661 0 86 12 2 2 1 0 3084 44044 168656 0 0 0 5156 2744 4684 0 47 53 0 2 0 0 2876 44048 169144 0 0 0 34 2804 5185 0 37 55 8 1 0 0 3072 44048 168740 0 0 0 0 3068 5870 0 39 61 0 All normal upto this point and it may stay this way for 100s of MB, but then things go pear-shaped: 0 1 0 3732 44092 167768 0 0 0 16486 1162 3489 0 31 4 65 0 1 0 3252 44188 168184 0 0 0 728 423 481 0 1 0 99 0 1 0 2728 44264 168632 0 0 0 784 426 509 0 0 0 100 0 1 0 2968 44316 168540 0 0 0 728 394 489 0 0 0 100 0 1 0 3300 44396 168220 0 0 0 784 422 517 0 0 0 100 Does anyone have any ideas what might cause this and how I can help to get it fixed? Regards, Nigel -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
