> On Jun 6, 2017, at 4:15 PM, J. Bruce Fields <bfields@xxxxxxxxxxxx> wrote: > > On Tue, Jun 06, 2017 at 03:45:59PM -0400, Chuck Lever wrote: >> >>> On Jun 6, 2017, at 3:41 PM, J. Bruce Fields <bfields@xxxxxxxxxxxx> wrote: >>> >>> On Tue, Jun 06, 2017 at 03:35:23PM -0400, Chuck Lever wrote: >>>> I filed https://bugzilla.linux-nfs.org/show_bug.cgi?id=306 >>>> >>>> To check memory allocation latency, I could always construct >>>> a framework around kmalloc and alloc_page. >>>> >>>> >>>> I've also found some bad behavior around proto=rdma,sec=krb5i. >>>> When I run a heavy I/O workload (fio, for example), every so >>>> often a read operation fails with EIO. I dug into it a little >>>> and MIC verification fails for these replies on the client. >>> >>> Do we still have the problem that the read data can change between the >>> time we calculate the MIC and the time we transmit the data to the >>> client? >> >> I don't see a problem with krb5p, which, if IIUC, would also >> fall victim to this situation, unless there is much stricter >> request serialization going on with krb5p. > > We turn off zero-copy by clearing RQ_SPLICE_OK in the krb5p case. Seems like this is the right answer for krb5i too. Shall I try that? >> Even so, how would I detect if this issue was present? > > Good question. If you knew the data and mic in the bad case, and had > some way to guess what the previous data might have been based on what > you knew about the test, then you could try mic's of likely older > versions of the data and see if you get a match.... That sounds hard. > > --b. -- Chuck Lever -- 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
