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vietnguyen
Posts: 1
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7/23/2007 2:23 PM
Hello, I have a small piece of code that uses the class and mailbox feature of system verilog. There is a sender task which generates a transactions and puts the transaction handle in a mailbox. The receiver task waits on a message from the mailbox and when one arrives it reads the message and print a message. The mailbox is bounded. The sender and receiver tasks are forked in an initial block. I seem to be experiencing a memory leak since the heap continues to grow. My understanding is system verilog handles garbage collection automatically. What am I doing wrong in my code. Attached is code: module mem_leak (); ///////////////////////////////////////////////////////////////////// // Generate clock and reset ///////////////////////////////////////////////////////////////////// reg clk; initial begin clk = 0; forever #(10/2) clk = ~clk; end ///////////////////////////////////////////////////////////////////// // Class declarations ///////////////////////////////////////////////////////////////////// class CpuCmd; time startT; time stopT; reg Ώ:0] cpu_id; reg btype; rand reg wr_rdn; rand reg ⎦:0] addr; rand reg [ 5:0] size; reg ⎳:0] packed_cmdΏ:0] reg ⎖:0] total_wd; extern task gen_cpu_addr; constraint cpucmd_constraint; endclass constraint CpuCmd::cpucmd_constraint { addr inside {Ύ : 2000]}; size inside {1, 4}; } task CpuCmd::gen_cpu_addr; startT = $time; stopT = startT; cpu_id = 0; btype = 0; packed_cmdΎ] = {btype,wr_rdn,3'h0,addr,2'h0,size}; packed_cmdΏ] = 40'h0; total_wd = size; endtask ///////////////////////////////////////////////////////////////////// // Declarations ///////////////////////////////////////////////////////////////////// // Command queue to hold transactions mailbox cmdQ; ///////////////////////////////////////////////////////////////////// // Main client loop ///////////////////////////////////////////////////////////////////// initial begin repeat (20) @(posedge clk); cmdQ = new(4); // bounded mailbox repeat (20) @(posedge clk); fork begin $display("INFO: Fork Sender"); sender; end begin $display("INFO: Fork receiver"); receiver; end join end /////////////////////////////////////////// // Sender /////////////////////////////////////////// task sender; int val; CpuCmd Scmd; while (1) begin repeat (1000) @(posedge clk); Scmd = new; val = Scmd.randomize(); if (val == 0) begin $display("Scmd randomization failed at %0t", $time); @(posedge clk); $finish; end Scmd.gen_cpu_addr(); // generate a command cmdQ.put(Scmd); // put command into mailbox $display("Sent message at %0t", $time); end endtask /////////////////////////////////////////// // Receiver /////////////////////////////////////////// task receiver; CpuCmd Rcmd; while (1) begin @(posedge clk); cmdQ.get(Rcmd); // Get a message from the mailbox $display("Received message at %0t", $time); end endtask endmodule

stephenh
Posts: 77
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8/01/2007 10:00 AM
What exact version of IUS are you using? I tried running your code on IUS6.11s2 and 6.11s3, but didn't see any sign of increasing memory consumption. My tests ran for about 1.5h and passed hundreds of thousands of items through the mailbox. Maximum memory consumption was always 29.3 MB no matter how long the test ran for.

Steve H.

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Forums > Functional Verification > SystemVerilog > memory leak - IUS61 system verilog

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