Re: A new Critical Section for high contention situations

Keith,
Thank you for your comments. I am not agree with you about your claims below
:

You said "there is no synchroniztion", then, what does synchronization mean?
AFAIK, synchronization means "accepting only one thread to access certain
resource or functionality at a time". My object achive this, so, I think,
there is synchronization.

You said "there is no contention", then what does contention mean? AFAIK,
contention (in the current context) means "more than one thtread to attemp
to access certain resource or functionality at the same time". While using
my object, this condition is highly possible, so "there is contention".

You mentioned "race conditions" but, race conditions occurs on resources not
on synchronization objects.

Please correct me if I am in the wrong. I don't claim that this short
implementation is correct but your arguments are contradictory with my
knowledge.


"Keith Moore" <keithmo@xxxxxxxxxx> wrote in message
news:eTMyk0ptIHA.4260@xxxxxxxxxxxxxxxxxxxxxxx
Kürþat wrote:
Hi,

"CRITICAL_SECTION"s are ideal inter-thread syncronization solutions for
low-contention situations but as the contention increases the performance
falls down accordingly because of kernel transition. So developed a
simple syncronization object which always remains in user mode (at least
I think so). I tested both the CRITICAL_SECTION and my object with a high
contention schenario and I see my object gives ~%45 better results (with
a dual core CPU). Wow, cool! What do you think about my implementation?
Is there any obstacle to use it in a commercial software?

(I am not sure about originality of the implementation, it may be
implemented many times by many developers.)

Thanks in advance.

/////////////////////////////////////////////////////////////////////

#define OWNED 1
#define NOT_OWNED 0

class CRITICAL
{
private:
int m_nLock;

public:
CRITICAL () : m_nLock (NOT_OWNED) {}

void enter ()
{
if (InterlockedCompareExchange ((LONG * ) &m_nLock, OWNED,
NOT_OWNED) == OWNED)
{
Sleep (0);
}
}

void leave ()
{
InterlockedExchange ((LONG * ) &m_nLock, NOT_OWNED);
}
};

There's no contention with this lock because... uhh... there's no
synchronization. If enter() is called on an already-locked object, the
calling thread will call Sleep(0) *once* then return. Race conditions
galore will ensue.

KM



.

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