hashbrowncipher

#!/usr/bin/env python
import os

from pyroute2 import TaskStats
from pyroute2.netlink import NLM_F_REQUEST
from pyroute2.netlink.taskstats import tcmd
from pyroute2.netlink.taskstats import TASKSTATS_CMD_GET

clk_tck = os.sysconf('SC_CLK_TCK')
clk_tck_factor = int(1e9 / clk_tck)

hashbrowncipher

from collections import namedtuple
from time import sleep
import sys
import os

NICE_FIELD = 19 - 1
DELAYACCT_BLKIO_TICKS_FIELD = 42 - 1

clk_tck_factor = int(1e9 / os.sysconf('SC_CLK_TCK'))

hashbrowncipher

$ sudo gdb --pid=$PID -ex 'gcore' -ex 'detach' -ex 'quit'

hashbrowncipher

description "Cassandra"

start on (local-filesystems and net-device-up IFACE!=lo)
stop on runlevel [06]

limit nofile 1000000 1000000
limit memlock unlimited unlimited

setuid cassandra

hashbrowncipher

Eden Sizing

There are limits to the size that Eden is allowed to be. Those limits are calculated in calculate_default_min_length:
G1YoungGenSizer::recalculate_min_max_young_length -> G1YoungGenSizer::calculate_default_min_length

G1CollectorPolicy::update_young_list_target_length is responsible for
determining the actual size of the young list. If doing a young GC, it will
call G1CollectorPolicy::calculate_young_list_target_length. This function
attempts to find the largest eden size that will allow (predicted) GC pauses to
remain under the pause time target. Presumably after a certain eden size, there

hashbrowncipher

Latency numbers every programmer should know

L1 cache reference ......................... 0.5 ns
Branch mispredict ............................ 5 ns
L2 cache reference ........................... 7 ns
Mutex lock/unlock ........................... 25 ns
Main memory reference ...................... 100 ns             
Compress 1K bytes with Zippy ............. 3,000 ns  =   3 µs
Send 2K bytes over 1 Gbps network ....... 20,000 ns  =  20 µs
SSD random read ........................ 150,000 ns  = 150 µs

Read 1 MB sequentially from memory ..... 250,000 ns = 250 µs

hashbrowncipher

//A parallel version of find(1), implementing a DFS-ish over cwd.
//Compile with -lpthread

#include <dirent.h>
#include <fcntl.h>
#include <pthread.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>

hashbrowncipher

$ sudo ./ocperf.py stat -e cpu_clk_thread_unhalted.ref_xclk,cpu_clk_thread_unhalted.ref_xclk_any,cpu_clk_unhalted.one_thread_active -a -- sleep 5
perf stat -e cpu/event=0x3c,umask=0x1,name=cpu_clk_thread_unhalted_ref_xclk/,cpu/event=0x3c,umask=0x1,any=1,name=cpu_clk_thread_unhalted_ref_xclk_any/,cpu/event=0x3c,umask=0x2,name=cpu_clk_unhalted_one_thread_active/ -a -- sleep 5

 Performance counter stats for 'system wide':

       295,538,267 cpu_clk_thread_unhalted_ref_xclk                                    [100.00%]
       579,495,176 cpu_clk_thread_unhalted_ref_xclk_any                                    [100.00%]
       283,950,270 cpu_clk_unhalted_one_thread_active

       5.000637559 seconds time elapsed

hashbrowncipher

package com.josnyder;

import java.lang.management.ManagementFactory;
import javax.management.InstanceAlreadyExistsException;
import javax.management.MBeanServer;
import javax.management.ObjectName;
import org.apache.cassandra.service.CassandraDaemon;

class HotspotMBeanCassandraDaemon extends CassandraDaemon {
    protected void setup() {

hashbrowncipher

diff --git a/src/main/java/com/tagtraum/perf/gcviewer/view/renderer/TotalTenuredRenderer.java b/src/main/java/com/tagtraum/perf/gcviewer/view/renderer/TotalTenuredRenderer.java
index 344965d..f8e31a0 100644
--- a/src/main/java/com/tagtraum/perf/gcviewer/view/renderer/TotalTenuredRenderer.java
+++ b/src/main/java/com/tagtraum/perf/gcviewer/view/renderer/TotalTenuredRenderer.java
@@ -49,6 +49,8 @@ public class TotalTenuredRenderer extends PolygonChartRenderer {
                         polygon.addPoint(0, (double)tenured.getTotal());
                     }
                     polygon.addPoint(tenured.getTimestamp() - model.getFirstPauseTimeStamp() + event.getPause(),
+                            lastTotal);
+                    polygon.addPoint(tenured.getTimestamp() - model.getFirstPauseTimeStamp() + event.getPause(),