Hi Sam-
I've tested on Fedora 12 (kernel 2.6.32.26-175) and Ubuntu 10.10 (kernel
2.6.35-24) with the same result on both.
Michael Moore has also been helping with this - I haven't been copying
the group as it's been a lot of details. But I will when we figure out
the issue!
-crispy
On 12/20/2010 11:31 AM, Sam Lang wrote:
Hi Chris,
This looks like it might be an issue with writev in the kernel. Are you
running RHEL5 by chance?
-sam
On Dec 15, 2010, at 8:39 AM, Chris Poultney wrote:
Sure - it's attached. I ran exactly the code I posted earlier.
-crispy
On 12/14/2010 07:25 PM, Sam Lang wrote:
Hi Chris,
Would you be willing to run your test with strace and post the output? That
will help us figure out what read/write system calls PVFS is getting from your
app.
Thanks,
-sam
On Dec 14, 2010, at 4:29 PM, Chris Poultney wrote:
All-
I'm having a problem where files written to a PVFS volume overwrite the
beginning of the file after some output has already been generated, as if
lseek() had been called mid-write. The overwriting behavior does not show up on
a regular ext3 volume. Sample code is attached. I'd like to know if anyone can
duplicate this behavior, because it looks like a bug.
Essentially what happens is this: given a large (1024+ character) string, I
write some portion of the string using a C++ ostream, then write another line:
out<< st.substr(0, N);
out<< "done";
If N< 1024, everything is fine. If N>= 1024, "done" is written at the
beginning of the file, overwriting what was there before.
I'd love to figure this out!
Cheers,
-crispy
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