Perhaps because P4 is already doing H/W prefetching?
http://www.tomshardware.com/2000/11/20/intel/page5.html
I ran the test program on an opteron 2.2G:
% ./a.out 10 16
Sum: -951304192: with prefetch on - duration: 81.166 ms
Sum: -951304192: with prefetch off - duration: 79.769 ms
Sum:
On Tue, 13 Sep 2005 Tom Lane wrote :
I wrote:
We could ameliorate this if there were a way to acquire ownership of the
cache line without necessarily winning the spinlock.
Another thought came to mind: maybe the current data layout for LWLocks
is bad. Right now, the spinlock that
On Tue, 13 Sep 2005 Tom Lane wrote :
Min Xu (Hsu) [EMAIL PROTECTED] writes:
...If this were the case, perhaps first fetch the spin lock with read-only
permission should have helped.
But the cmpb instruction in the 8.0 version of TAS would have done that,
and I think we've already
On Tue, 13 Sep 2005 Tom Lane wrote :
Min Xu (Hsu) [EMAIL PROTECTED] writes:
... As you said, however, experimental results
shows fetching read-only lines didn't help, which led me wonder whether the
second scenario your described was really happening.
I don't know --- we haven't tried
Neil and others,
It might be interesting to look at some of the papers by Michael
Scott et al. I am not an expert on non-blocking data structures,
but the following page seems interesting:
http://www.cs.rochester.edu/u/scott/synchronization/
esp. (7) nonblocking dual data structures, which
On Tue, 25 Jan 2005 Neil Conway wrote :
Amazingly, there *are* lock-free hash table
algorithms (e.g. [1]), but at first glance they seem pretty complex, and
It is a little scary when I read the lock-free hash table algorithm
needs a theorem prover to prove its correctness. I'd guess maintaining
Tom Lane wrote:
While investigating Satoshi Okada's bug report here
...
What I am thinking of doing to fix the problem is to introduce
a new LWLock that RecordTransactionCommit will take a shared lock on
before writing its WAL record, and not release until it has updated
pg_clog. Checkpoint
I am also interested in this so I want to make some comments.
On Thu, 22 Apr 2004 Shachar Shemesh wrote :
Found it:
http://developer.kde.org/~sewardj/docs-2.0.0/mc_main.html, section 3.3.2
It is important to understand that your program can copy around junk
(uninitialised) data to its
