Hi all,
I am making a call to *llapi_layout_get_by_fd()* from each rank of a 16
rank MPI job. One rank per node.
About 75% of the time, one of the ranks, typically rank 0, takes a very
long time to complete this call. I have placed fprintf() calls with
wall clock timers around the call. If it does take a long time it is
generally about 260 seconds. Otherwise it takes only micro-seconds.
How I access llapi_layout_get_by_fd() :
liblustreapi = dlopen("liblustreapi.so", RTLD_LAZY ) ;
LLAPI.layout_get_by_fd = dlsym( liblustreapi, "llapi_layout_get_by_fd" ) ;
How I call llapi_layout_get_by_fd() :
if(dbg)fprintf(stderr,"%s %12.8f %s() before
LLAPI.layout_get_by_fd()\n",host,rtc(),__func__);
struct llapi_layout *layout = (*LLAPI.layout_get_by_fd)( fd, 0);
if(dbg)fprintf(stderr,"%s %12.8f %s() after
LLAPI.layout_get_by_fd()\n",host,rtc(),__func__);
The resulting prints from rank 0 :
r401i2n10 7.22477698 LustreLayout_get_by_fd() before
LLAPI.layout_get_by_fd()
r401i2n10 269.52539992 LustreLayout_get_by_fd() after
LLAPI.layout_get_by_fd()
Any ideas on what might be triggering this. The layout returned seems
to be correct every time, whether it takes a long time or not. The
layout returned has the correct striping information, but the component
has no OSTs as the component has yet to be instantiated for the new file.
cat /sys/fs/lustre/version
2.12.8_ddn12
_______________________________________________
lustre-discuss mailing list
[email protected]
http://lists.lustre.org/listinfo.cgi/lustre-discuss-lustre.org
