On 06.03.2012 17:12, Tom Lane wrote:
Heikki Linnakangas<heikki.linnakan...@enterprisedb.com>  writes:
On 06.03.2012 14:52, Fujii Masao wrote:
This also strikes me that the usage of the spinlock insertpos_lck might
not be OK in ReserveXLogInsertLocation() because a few dozen instructions
can be performed while holding the spinlock....

I admit that block is longer than any of our existing spinlock blocks.
However, it's important for performance. I tried using a lwlock earlier,
and that negated the gains. So if that's a serious objection, then let's
resolve that now before I spend any more time on other aspects of the
patch. Any ideas how to make that block shorter?

How long is the current locked code exactly --- does it contain a loop?

Perhaps best if you take a look for yourself, the function is called ReserveXLogInsertLocation() in patch. It calls a helper function called AdvanceXLogRecPtrToNextPage(ptr), which is small and could be inlined. It does contain one loop, which iterates once for every WAL page the record crosses.

  Heikki Linnakangas
  EnterpriseDB   http://www.enterprisedb.com

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