SQL Modal Problem

Hi,
I have a form that just displays some data regarding web logs. My SQL is not too hot so i hope somebody can point me in the right direction. I have a DB table that amongst others has a server name and an execution times column. There are thousands of records each for every second within a particular week. I basically want to be able to select for each distinct server name the most popular execution time. For example if for server 'A' there are 5 records with an execution time of 0.5secs and 4 records with an execution time of 0.35secs then i want to return a record with the execution time of 0.5secs. However i want to be able to do this for every different occurrence of server name in my table. So i want to return records for server name 'B' and server name 'C' etc.

Here is the SQL i have at the moment but it only returns the most popular or most occurring execution time in the table not the most popular execution time for EVERY server name in my table. For example

Server_Name | Execution_Time
-------------------------------------
A | 0.5


<code>
SELECT DISTINCT instance, exec_time AS modal
FROM Llserverlogs
GROUP BY instance, exec_time
HAVING (COUNT(*) >= ALL
(SELECT COUNT(*)
FROM llserverlogs
GROUP BY instance, exec_time))
</code>

Hope somebody can help and thanks in davance for the help.