How to calculate the hit ratio?

Good day everyone,

Based on the below screenshot I want to calculate the hit ratio. The formula for calculating the value would be: cachehits+cachemisses/cachehits.

For 1st second I get two types: Cachehits and Cachemisses. In this way I have the data for all the nodes in the network that I simulated. I want to know is there anyway in matlab that I can give the formula once and I can get the values for all my rows?

Please let me know. Thank you.

Answer 1

[sudobash]

Hello!

As per my understanding, the Hit Ratio for the entire network needs to be computed. Here is a solution:

%% Example Input
inputTable = table();
inputTable.Time = [1;1;2;2;3;3;4;4];
inputTable.Node = ["R7";"R7";"R7";"R7";"R7";"R7";"R7";"R7"];
inputTable.Type = ["CacheHits";"CacheMisses";"CacheHits";"CacheMisses";"CacheHits";"CacheMisses";"CacheHits";"CacheMisses"];
inputTable.Packets = [1;22;4;15;9;15;9;13];
inputTable

inputTable = 8×4 table
    Time    Node        Type         Packets
    ____    ____    _____________    _______

     1      "R7"    "CacheHits"         1   
     1      "R7"    "CacheMisses"      22   
     2      "R7"    "CacheHits"         4   
     2      "R7"    "CacheMisses"      15   
     3      "R7"    "CacheHits"         9   
     3      "R7"    "CacheMisses"      15   
     4      "R7"    "CacheHits"         9   
     4      "R7"    "CacheMisses"      13   

%% Solution
% Find the total number of cache hits
totalCacheHits = sum(inputTable(inputTable.Type == "CacheHits",:).Packets)

totalCacheHits = 23

% Find the total number of cache misses
totalCacheMisses = sum(inputTable(inputTable.Type == "CacheMisses",:).Packets)

totalCacheMisses = 65

% Compute the Hit Ratio using the formula
hitRatio = (totalCacheMisses + totalCacheHits)/totalCacheHits

hitRatio = 3.8261

You can also find the hit ratio for each node by selecting only specific nodes like this:

R7CacheMisses = sum(inputTable(inputTable.Type == "CacheMisses" & inputTable.Node == "R7",:).Packets)

Hope this addresses your question.

[Sai Gautam Mandapati]

Thanks for answering my question. So, I want to create a sepearte column with the label Cache Hit Ratio and I want the formula hit ratio applied to the entire column where it takes the first two rows:cachehits and cachemisses of 1st second and give me the value of hit ratio and following that for 2nd second for the same node.

[Sai Gautam Mandapati]

Yes, that's exactly what I'm looking for. For the consecutive values it would change right? 4+15/4 the hit ratio would be 4.75 and what do you mean by the same value of hit ratio fo agiven time instant?

[Sai Gautam Mandapati]

Hi @sudobash @Subash, I need to calculate the hit ratio for every time instant. Is there anyway I can do that?

[sudobash]

Hi!

As per my understanding, I would suggest you reformat your table and find hit ratio in this way :

%% Example Input
inputTable = table();
inputTable.Time = [1;2;3;4];
inputTable.Node = ["R7";"R7";"R7";"R7"];
inputTable.Hit = [1;4;9;9];         % Hit is the number of packets of the type "CacheHit"
inputTable.Miss = [22;15;15;13];    % Miss is the number of packets of the type "CacheMiss"
inputTable

inputTable = 4×4 table
    Time    Node    Hit    Miss
    ____    ____    ___    ____

     1      "R7"     1      22 
     2      "R7"     4      15 
     3      "R7"     9      15 
     4      "R7"     9      13 

inputTable.HitRatio = (inputTable.Hit + inputTable.Miss)./inputTable.Hit

inputTable = 4×5 table
    Time    Node    Hit    Miss    HitRatio
    ____    ____    ___    ____    ________

     1      "R7"     1      22          23 
     2      "R7"     4      15        4.75 
     3      "R7"     9      15      2.6667 
     4      "R7"     9      13      2.4444 

If you wish not to reformat, then you could use the following workaround:

%% Example Input
inputTable = table();
inputTable.Time = [1;1;2;2;3;3;4;4];
inputTable.Node = ["R7";"R7";"R7";"R7";"R7";"R7";"R7";"R7"];
inputTable.Type = ["CacheHits";"CacheMisses";"CacheHits";"CacheMisses";"CacheHits";"CacheMisses";"CacheHits";"CacheMisses"];
inputTable.Packets = [1;22;4;15;9;15;9;13];
inputTable;

for i = 1:2:height(inputTable)
    inputTable.HitRatio(i) = (inputTable.Packets(i)+inputTable.Packets(i+1))/inputTable.Packets(i);
    inputTable.HitRatio(i+1) = (inputTable.Packets(i)+inputTable.Packets(i+1))/inputTable.Packets(i);
end
inputTable

inputTable = 8×5 table
    Time    Node        Type         Packets    HitRatio
    ____    ____    _____________    _______    ________

     1      "R7"    "CacheHits"         1            23 
     1      "R7"    "CacheMisses"      22            23 
     2      "R7"    "CacheHits"         4          4.75 
     2      "R7"    "CacheMisses"      15          4.75 
     3      "R7"    "CacheHits"         9        2.6667 
     3      "R7"    "CacheMisses"      15        2.6667 
     4      "R7"    "CacheHits"         9        2.4444 
     4      "R7"    "CacheMisses"      13        2.4444 

Hope this solves your question.