Hey Samuel,
The "PGLog::check()" is now no longer visible in profiling, so it helped
for that. Unfortunately, it doesn't seem to have helped to bring down
the OSD's CPU-loading much. Leveldb still uses much more than in
Cuttlefish. On my test-cluster, I didn't notice any difference in the
RBD bench-results, either, so I have to assume that it didn't help
performance much.
Here's the `perf top' I took just now on my production-cluster with your
new version, under regular load. Also note the "memcmp" and "memcpy",
which also don't show up when running a Cuttlefish-OSD:
15.65% [kernel] [k]
intel_idle
7.20% libleveldb.so.1.9 [.]
0x3ceae
6.28% libc-2.11.3.so [.]
memcmp
5.22% [kernel] [k]
find_busiest_group
3.92% kvm [.]
0x2cf006
2.40% libleveldb.so.1.9 [.]
leveldb::InternalKeyComparator::Compar
1.95% [kernel] [k]
_raw_spin_lock
1.69% [kernel] [k]
default_send_IPI_mask_sequence_phys
1.46% libc-2.11.3.so [.]
memcpy
1.17% libleveldb.so.1.9 [.]
leveldb::Block::Iter::Next()
1.16% [kernel] [k]
hrtimer_interrupt
1.07% [kernel] [k]
native_write_cr0
1.01% [kernel] [k]
__hrtimer_start_range_ns
1.00% [kernel] [k]
clockevents_program_event
0.93% [kernel] [k]
find_next_bit
0.93% libstdc++.so.6.0.13 [.]
std::string::_M_mutate(unsigned long,
0.89% [kernel] [k]
cpumask_next_and
0.87% [kernel] [k]
__schedule
0.85% [kernel] [k]
_raw_spin_unlock_irqrestore
0.85% [kernel] [k]
do_select
0.84% [kernel] [k]
apic_timer_interrupt
0.80% [kernel] [k]
fget_light
0.79% [kernel] [k]
native_write_msr_safe
0.76% [kernel] [k]
_raw_spin_lock_irqsave
0.66% libc-2.11.3.so [.]
0xdc6d8
0.61% libpthread-2.11.3.so [.]
pthread_mutex_lock
0.61% [kernel] [k]
tg_load_down
0.59% [kernel] [k]
reschedule_interrupt
0.59% libsnappy.so.1.1.2 [.]
snappy::RawUncompress(snappy::Source*,
0.56% libstdc++.so.6.0.13 [.] std::string::append(char
const*, unsig
0.54% [kvm_intel] [k]
vmx_vcpu_run
0.53% [kernel] [k]
copy_user_generic_string
0.53% [kernel] [k]
load_balance
0.50% [kernel] [k]
rcu_needs_cpu
0.45% [kernel] [k] fput
Regards,
Oliver
On ma, 2013-08-26 at 23:33 -0700, Samuel Just wrote:
> I just pushed a patch to wip-dumpling-log-assert (based on current
> dumpling head). I had disabled most of the code in PGLog::check() but
> left an (I thought) innocuous assert. It seems that with (at least)
> g++ 4.6.3, stl list::size() is linear in the size of the list, so that
> assert actually traverses the pg log on each operation. The patch in
> wip-dumpling-log-assert should disable that assert as well by default.
> Let me know if it helps.
>
> It should be built within an hour of this email.
> -Sam
>
> On Mon, Aug 26, 2013 at 10:46 PM, Matthew Anderson
> <[email protected]> wrote:
> > Hi Guys,
> >
> > I'm having the same problem as Oliver with 0.67.2. CPU usage is around
> > double that of the 0.61.8 OSD's in the same cluster which appears to
> > be causing the performance decrease.
> >
> > I did a perf comparison (not sure if I did it right but it seems ok).
> > Both hosts are the same spec running Ubuntu 12.04.1 (3.2 kernel),
> > journal and osd data is on an SSD, OSD's are in the same pool with the
> > same weight and the perf tests were run at the same time on a
> > realworld load consisting of RBD traffic only.
> >
> > Dumpling -
> >
> > Events: 332K cycles
> > 17.93% ceph-osd libc-2.15.so [.] 0x15d523
> > 17.03% ceph-osd ceph-osd [.] 0x5c2897
> > 4.66% ceph-osd ceph-osd [.]
> > leveldb::InternalKeyComparator::Compare(leveldb::Slice const&, level
> > 3.46% ceph-osd ceph-osd [.] leveldb::Block::Iter::Next()
> > 2.70% ceph-osd libstdc++.so.6.0.16 [.]
> > std::string::_M_mutate(unsigned long, unsigned long, unsigned long)
> > 2.60% ceph-osd ceph-osd [.] PGLog::check()
> > 2.57% ceph-osd [kernel.kallsyms] [k] __ticket_spin_lock
> > 2.49% ceph-osd ceph-osd [.] ceph_crc32c_le_intel
> > 1.93% ceph-osd libsnappy.so.1.1.2 [.]
> > snappy::RawUncompress(snappy::Source*, char*)
> > 1.53% ceph-osd libstdc++.so.6.0.16 [.] std::string::append(char
> > const*, unsigned long)
> > 1.47% ceph-osd libtcmalloc.so.0.1.0 [.] operator new(unsigned long)
> > 1.33% ceph-osd [kernel.kallsyms] [k] copy_user_generic_string
> > 0.98% ceph-osd libtcmalloc.so.0.1.0 [.] operator delete(void*)
> > 0.90% ceph-osd libstdc++.so.6.0.16 [.] std::string::assign(char
> > const*, unsigned long)
> > 0.75% ceph-osd libstdc++.so.6.0.16 [.]
> > std::string::_M_replace_safe(unsigned long, unsigned long, char cons
> > 0.58% ceph-osd [kernel.kallsyms] [k] wait_sb_inodes
> > 0.55% ceph-osd ceph-osd [.]
> > leveldb::Block::Iter::Valid() const
> > 0.51% ceph-osd libtcmalloc.so.0.1.0 [.]
> > tcmalloc::ThreadCache::ReleaseToCentralCache(tcmalloc::ThreadCache::
> > 0.50% ceph-osd libtcmalloc.so.0.1.0 [.]
> > tcmalloc::CentralFreeList::FetchFromSpans()
> > 0.47% ceph-osd libstdc++.so.6.0.16 [.] 0x9ebc8
> > 0.46% ceph-osd libc-2.15.so [.] vfprintf
> > 0.45% ceph-osd [kernel.kallsyms] [k] find_busiest_group
> > 0.45% ceph-osd libstdc++.so.6.0.16 [.]
> > std::string::resize(unsigned long, char)
> > 0.43% ceph-osd libpthread-2.15.so [.] pthread_mutex_unlock
> > 0.41% ceph-osd [kernel.kallsyms] [k] iput_final
> > 0.40% ceph-osd ceph-osd [.]
> > leveldb::Block::Iter::Seek(leveldb::Slice const&)
> > 0.39% ceph-osd libc-2.15.so [.] _IO_vfscanf
> > 0.39% ceph-osd ceph-osd [.] leveldb::Block::Iter::key()
> > const
> > 0.39% ceph-osd libtcmalloc.so.0.1.0 [.]
> > tcmalloc::CentralFreeList::ReleaseToSpans(void*)
> > 0.37% ceph-osd libstdc++.so.6.0.16 [.] std::basic_ostream<char,
> > std::char_traits<char> >& std::__ostream_in
> >
> >
> > Cuttlefish -
> >
> > Events: 160K cycles
> > 7.53% ceph-osd [kernel.kallsyms] [k] __ticket_spin_lock
> > 6.26% ceph-osd libc-2.15.so [.] 0x89115
> > 3.06% ceph-osd ceph-osd [.] ceph_crc32c_le
> > 2.66% ceph-osd libtcmalloc.so.0.1.0 [.] operator new(unsigned long)
> > 2.46% ceph-osd [kernel.kallsyms] [k] find_busiest_group
> > 1.80% ceph-osd libtcmalloc.so.0.1.0 [.] operator delete(void*)
> > 1.42% ceph-osd [kernel.kallsyms] [k] try_to_wake_up
> > 1.27% ceph-osd ceph-osd [.] 0x531fb6
> > 1.21% ceph-osd libstdc++.so.6.0.16 [.] 0x9ebc8
> > 1.14% ceph-osd [kernel.kallsyms] [k] wait_sb_inodes
> > 1.02% ceph-osd libc-2.15.so [.] _IO_vfscanf
> > 1.01% ceph-osd [kernel.kallsyms] [k] update_shares
> > 0.98% ceph-osd [kernel.kallsyms] [k] filemap_fdatawait_range
> > 0.90% ceph-osd libstdc++.so.6.0.16 [.] std::basic_ostream<char,
> > std::char_traits<char> >& std
> > 0.89% ceph-osd [kernel.kallsyms] [k] iput_final
> > 0.79% ceph-osd libstdc++.so.6.0.16 [.] std::basic_string<char,
> > std::char_traits<char>, std::a
> > 0.79% ceph-osd [kernel.kallsyms] [k] copy_user_generic_string
> > 0.78% ceph-osd libc-2.15.so [.] vfprintf
> > 0.70% ceph-osd libtcmalloc.so.0.1.0 [.]
> > tcmalloc::ThreadCache::ReleaseToCentralCache(tcmalloc:
> > 0.69% ceph-osd [kernel.kallsyms] [k] __d_lookup_rcu
> > 0.69% ceph-osd libtcmalloc.so.0.1.0 [.]
> > tcmalloc::CentralFreeList::FetchFromSpans()
> > 0.66% ceph-osd [kernel.kallsyms] [k] igrab
> > 0.63% ceph-osd [kernel.kallsyms] [k] update_cfs_load
> > 0.63% ceph-osd [kernel.kallsyms] [k] link_path_walk
> >
> > If you'd like some more tests run just let me know, more than happy to help
> >
> > Thanks
> > -Matt
>
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