Re: Wait free LW_SHARED acquisition

--On 30. September 2013 19:00:06 +0200 Andres Freund
<andres(at)2ndquadrant(dot)com> wrote:

>> HEAD (default):
>>
>> tps = 181738.607247 (including connections establishing)
>> tps = 182665.993063 (excluding connections establishing)
>>
>> HEAD (padding + 16 partitions + your lwlocks patch applied):
>>
>> tps = 269328.259833 (including connections establishing)
>> tps = 270685.666091 (excluding connections establishing)
>>
>> So, still an improvement but far away from what you got. Do you have some
>> other tweaks in your setup?
>
> The only relevant setting changed was -c shared_buffers=1GB, no other
> patches applied. At which scale did you pgbench -i?

I've used a scale factor of 10 (i recall you've mentioned using the same
upthread...).

Okay, i've used 2GB shared buffers, repeating with your setting i get a far
more noticable speedup:

tps = 346292.008580 (including connections establishing)
tps = 347997.073595 (excluding connections establishing)

Here's the perf output:

+ 4.34% 207112 postgres postgres [.]
AllocSetAlloc
+ 4.07% 194476 postgres libc-2.13.so [.] 0x127b33
+ 2.59% 123471 postgres postgres [.]
SearchCatCache
+ 2.49% 118974 pgbench libc-2.13.so [.] 0x11aaef
+ 2.48% 118263 postgres postgres [.]
GetSnapshotData
+ 2.46% 117646 postgres postgres [.]
base_yyparse
+ 2.02% 96546 postgres postgres [.]
MemoryContextAllocZeroAligned
+ 1.58% 75326 postgres postgres [.]
AllocSetFreeIndex
+ 1.23% 58587 postgres postgres [.]
hash_search_with_hash_value
+ 1.01% 48391 postgres postgres [.] palloc
+ 0.93% 44258 postgres postgres [.]
LWLockAttemptLock
+ 0.91% 43575 pgbench libc-2.13.so [.] free
+ 0.89% 42484 postgres postgres [.]
nocachegetattr
+ 0.89% 42378 postgres postgres [.] core_yylex
+ 0.88% 42001 postgres postgres [.]
_bt_compare
+ 0.84% 39997 postgres postgres [.]
expression_tree_walker
+ 0.76% 36533 postgres postgres [.]
ScanKeywordLookup
+ 0.74% 35515 pgbench libc-2.13.so [.] malloc
+ 0.64% 30715 postgres postgres [.]
LWLockRelease
+ 0.56% 26779 postgres postgres [.]
fmgr_isbuiltin
+ 0.54% 25681 pgbench [kernel.kallsyms] [k] _spin_lock
+ 0.48% 22836 postgres postgres [.] new_list
+ 0.48% 22700 postgres postgres [.] hash_any
+ 0.47% 22378 postgres postgres [.]
FunctionCall2Coll
+ 0.46% 22095 postgres postgres [.] pfree
+ 0.44% 20929 postgres postgres [.] palloc0
+ 0.43% 20592 postgres postgres [.]
AllocSetFree
+ 0.40% 19495 postgres [unknown] [.] 0x81cf2f
+ 0.40% 19247 postgres postgres [.]
hash_uint32
+ 0.38% 18227 postgres postgres [.] PinBuffer
+ 0.38% 18022 pgbench [kernel.kallsyms] [k] do_select

--
Thanks

Bernd