Thanks Chris!
Yasumasa 2019年2月21日(木) 11:08 Chris Plummer <chris.plum...@oracle.com>: > Ok. The changes look fine to me then. > > thanks, > > Chris > > On 2/20/19 6:02 PM, Yasumasa Suenaga wrote: > > Hi Chris, > > > > I grep'ed with "MAP_SHARED" on jdk/src. > > Shared memory is used in ZGC (ZBackingFile and ZPhysicalMemoryBacking) > > and in FileChannel::map at least. > > > > I think we have memory footprint concern about them, but shared memory > > should be dumped. > > If we did not get them, we cannot analyze ZGC related behavior and > > other code which uses shared memory. > > (We can pass FD to os::reserve_memory - it will use shared memory if > > FD is passed.) > > > > Thus I want to introduce `DumpSharedMappingsInCore` for dumping shared > > memory and set it to true by default. > > > > > > Thanks, > > > > Yasumasa > > > > > > 2019年2月21日(木) 3:10 Chris Plummer <chris.plum...@oracle.com>: > >> [adding runtime] > >> > >> Hi Yasumasa, > >> > >> Overall looks good. Just a couple of questions. > >> > >> Do we have the same footprint concerns with the shared mappings as we > >> did with the private mappings? If not, possibly it doesn't need an > >> option and should always be enabled. > >> > >> thanks, > >> > >> Chris > >> > >> On 2/20/19 12:03 AM, Yasumasa Suenaga wrote: > >>> Hi all, > >>> > >>> Please review this webrev: > >>> > >>> JBS: https://bugs.openjdk.java.net/browse/JDK-8219414 > >>> webrev: > http://cr.openjdk.java.net/~ysuenaga/JDK-8219414/webrev.00/ > >>> > >>> I tried to get PerfCounter values via `jhsdb jsnap` from core image > >>> which is generated by `gcore` (provided by GDB), but I encountered > >>> UnmappedAddressException. > >>> > >>> It is caused by `generate-core-file` on GDB regards `coredump_filter` > on procfs. > >>> > >>> > https://sourceware.org/gdb/onlinedocs/gdb/Core-File-Generation.html > >>> > >>> JDK-8200613 introduced `DumpPrivateMappingsInCore` for CDS. I want to > >>> introduce `DumpSharedMappingsInCore` for shared memory mapping. > >>> > >>> Currently `DumpPrivateMappingsInCore` affects when `UseSharedSpaces` > is enabled. > >>> I want `DumpPrivateMappingsInCore` to affect independently in this > >>> change because file-backed private memory which is not CDS might be > >>> useful in the future. > >>> > >>> > >>> Thanks, > >>> > >>> Yasumasa > >> > > >
