Add 12th lab

CMakeLists.txt

@@ -21,4 +21,5 @@ define_lab(lab6)
 define_lab(lab7)
 define_lab(lab8)
 define_lab(lab9)
-define_lab(lab10)
+define_lab(lab10)
+define_lab(lab12)

README.md

@@ -8,9 +8,11 @@
 - [Лабораторная работа 5](lab5/README.md)
 - [Лабораторная работа 6](lab6/README.md)
 - [Лабораторная работа 7](lab7/README.md)
+- [Лабораторная работа 8](lab8/README.md)
 - [Лабораторная работа 9](lab9/README.md)
 - [Лабораторная работа 10](lab10/README.md)
 - [Лабораторная работа 11](lab11/README.md)
+- [Лабораторная работа 12](lab12/README.md)
 
 ## Запуск
 

lab12/.execme

@@ -0,0 +1,10 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+IFS=$'\n\t'
+
+pushd "$1" > /dev/null
+
+./lab12_cache.c_run > ./data && lscpu && cat /proc/cpuinfo && python2 ./graph_data.py
+
+popd > /dev/null

lab12/CMakeLists.txt

@@ -0,0 +1,36 @@
+cmake_minimum_required(VERSION 3.16)
+set(CMAKE_C_STANDARD 11)
+
+# Lab name
+set(LAB_NAME "lab12")
+
+# Lab tasks
+list(APPEND SOURCE_FILES
+        cache.c
+        )
+list(APPEND NON_COMPILABLE_SRC
+        .execme
+        graph_data.py
+        thinkplot.py
+        )
+
+### Here goes the template
+
+project("${LAB_NAME}" C)
+
+add_custom_target("${LAB_NAME}")
+
+foreach (file IN LISTS SOURCE_FILES)
+    add_executable("${LAB_NAME}_${file}_run" "${file}")
+    add_dependencies("${LAB_NAME}" "${LAB_NAME}_${file}_run")
+endforeach ()
+
+foreach (file IN LISTS NON_COMPILABLE_SRC)
+    add_custom_command(
+            TARGET "${LAB_NAME}" POST_BUILD
+            DEPENDS "${file}"
+            COMMAND ${CMAKE_COMMAND} -E copy
+            "${CMAKE_CURRENT_SOURCE_DIR}/${file}"
+            "${CMAKE_CURRENT_BINARY_DIR}/${file}"
+    )
+endforeach ()

lab12/README.md

@@ -0,0 +1,53 @@
+# Лабораторная работа №12
+
+>  Проанализируйте cache.c  и с ее использованием исследуйте параметры кэша на вашем компьютере. Для этого 
+>  1. постройте графики времени доступа как функции длины массива, шага выборки и размера буфера. 
+>  2. на их основе сформулируйте обоснованные гипотезы о  размере кэша, размере блока, наличию кэша более высокого уровня. 
+>  3. сравните свои оценки с реальными значениями, полученными через вызов системных функций или из технического описания вашего компьютера.
+
+График:
+
+![](g1.png)
+
+Как видно из графика, стремительный рост access time происходит на 2^22 B, что примерно равно 4 мегабайтам.
+Из этого можно предположить, что размер кэша -- 4Мб. На размере блока выше 64 байт происходит увеличение access time,
+что может быть связано с тем, что физический размер блока -- 64 байта. Также наблюдаются ускорения при размере 2^20 и 
+2^21, что может говорить о существовании некоторых кэшей размером в 1 и 2 Мб.
+
+Вывод `cat /proc/cpuinfo`:
+```text
+...
+cache size      : 3072 KB
+bugs            : cpu_meltdown spectre_v1 spectre_v2 spec_store_bypass l1tf mds swapgs itlb_multihit srbds
+bogomips        : 3792.26
+clflush size    : 64
+cache_alignment : 64
+address sizes   : 39 bits physical, 48 bits virtual
+...
+```
+
+Вывод `lscpu`:
+```text
+...
+L1d cache:                       64 KiB
+L1i cache:                       64 KiB
+L2 cache:                        512 KiB
+L3 cache:                        3 MiB
+Vulnerability Itlb multihit:     KVM: Mitigation: Split huge pages
+Vulnerability L1tf:              Mitigation; PTE Inversion; VMX conditional cache flushes, SMT vulnerable
+Vulnerability Mds:               Mitigation; Clear CPU buffers; SMT vulnerable
+Vulnerability Meltdown:          Mitigation; PTI
+Vulnerability Spec store bypass: Mitigation; Speculative Store Bypass disabled via prctl and seccomp
+Vulnerability Spectre v1:        Mitigation; usercopy/swapgs barriers and __user pointer sanitization
+Vulnerability Spectre v2:        Mitigation; Full generic retpoline, IBPB conditional, IBRS_FW, STIBP conditional, RSB filling
+Vulnerability Srbds:             Mitigation; Microcode
+Vulnerability Tsx async abort:   Not affected
+...
+```
+
+Исходя из этих данных, можно предположить, что в связи с патчами для устранения уязвимостей процессора
+(Spectre, Meltdown, L1TF и прочие) график может не вполне корректно отражать реальное положение дел.
+
+Но выводы оказались достаточно приближены к действительности: мы видим два L1-кэша размера 64 Кб (не видно
+на графике, т.к. 2^16 Б меньше левой границы графика), L2-кэш размера 512 Кб (2^19 Б) и L3-кэш размера 3 Мб
+(~2^(21.6) Б).

lab12/cache.c

@@ -0,0 +1,72 @@
+/******************************************************************
+ *                CACHE project                                   *
+ *                                                                *
+ * Using this program, on as many different kinds of computers as *
+ * possible, investigate these cache parameters:                  *
+ *      -- total cache size                                       *
+ *      -- cache width                                            *
+ *      -- cache replacement policy                               *
+ ******************************************************************/
+
+/* I got this program from Brian Harvey, who teaches CS61C at
+   Berkeley.  He didn't put a copyright on it, but he should
+   at least get credit for it.  Thanks, Brian! */
+
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/times.h>
+#include <sys/types.h>
+#include <time.h>
+
+#define CACHE_MIN (32*1024) /* smallest cache */
+#define CACHE_MAX (32*1024*1024) /* largest cache */
+#define SAMPLE 10 /* to get a larger time sample */
+
+int x[CACHE_MAX]; /* array going to stride through */
+long clk_tck;
+ 
+double get_seconds() { /* routine to read time */
+    struct tms rusage;
+    times(&rusage); /* UNIX utility: time in clock ticks */
+    return (double) (rusage.tms_utime)/clk_tck;
+}
+
+int main() {
+    int register i, index, stride, limit, temp;
+    int steps, tsteps, csize;
+    double sec0, sec; /* timing variables */
+
+    clk_tck = sysconf(_SC_CLK_TCK);
+ 
+    for (csize=CACHE_MIN; csize <= CACHE_MAX; csize=csize*2) 
+	for (stride=1; stride <= csize/2; stride=stride*2) {
+	    sec = 0; /* initialize timer */
+	    limit = csize-stride+1; /* cache size this loop */
+     
+	    steps = 0;
+	    do { /* repeat until collect 1 second */
+		sec0 = get_seconds(); /* start timer */
+		for (i=SAMPLE*stride;i!=0;i=i-1) /* larger sample */
+		    for (index=0; index < limit; index=index+stride) 
+		        x[index] = x[index] + 1; /* cache access */
+		steps = steps + 1; /* count while loop iterations */
+		sec = sec + (get_seconds() - sec0);/* end timer */
+	    } while (sec < 1.0); /* until collect 1 second */
+     
+	    /* Repeat empty loop to loop subtract overhead */
+	    tsteps = 0; /* used to match no. while iterations */
+	    do { /* repeat until same no. iterations as above */
+		sec0 = get_seconds(); /* start timer */
+		for (i=SAMPLE*stride;i!=0;i=i-1) /* larger sample */
+		    for (index=0; index < limit; index=index+stride) 
+		        temp = temp + index; /* dummy code */
+		tsteps = tsteps + 1; /* count while iterations */
+		sec = sec - (get_seconds() - sec0);/* - overhead */
+	    } while (tsteps<steps); /* until = no. iterations */
+     
+	    printf("Size: %7ld Stride: %7ld read+write: %4.4lf ns\n",
+	       csize*sizeof(int), stride*sizeof(int),
+	       (double) sec*1e9/(steps*SAMPLE*stride*((limit-1)/stride+1)));
+	}; /* end of both outer for loops */
+}
+

lab12/graph_data.py

@@ -0,0 +1,20 @@
+import thinkplot
+import matplotlib.pyplot as pyplot
+
+d = {}
+for line in open('data'):
+    t = line.split()
+    size, stride, time = int(t[1]), int(t[3]), float(t[5])
+    d.setdefault(stride, []).append((size, time))
+
+
+thinkplot.PrePlot(num=7)
+for stride in sorted(d.keys()):
+    if stride >= 512: continue
+
+    xs, ys = zip(*d[stride])
+    thinkplot.plot(xs, ys, label=str(stride))
+    print stride, len(d[stride])
+
+pyplot.xscale('log', basex=2)
+thinkplot.show(xlabel='size (B)', ylabel='access time (ns)')

lab12/thinkplot.py

@@ -0,0 +1,504 @@
+"""This file contains code for use with "Think Stats",
+by Allen B. Downey, available from greenteapress.com
+
+Copyright 2010 Allen B. Downey
+License: GNU GPLv3 http://www.gnu.org/licenses/gpl.html
+"""
+
+import math
+import matplotlib
+import matplotlib.pyplot as pyplot
+import numpy as np
+
+# customize some matplotlib attributes
+#matplotlib.rc('figure', figsize=(4, 3))
+
+#matplotlib.rc('font', size=14.0)
+#matplotlib.rc('axes', labelsize=22.0, titlesize=22.0)
+#matplotlib.rc('legend', fontsize=20.0)
+
+#matplotlib.rc('xtick.major', size=6.0)
+#matplotlib.rc('xtick.minor', size=3.0)
+
+#matplotlib.rc('ytick.major', size=6.0)
+#matplotlib.rc('ytick.minor', size=3.0)
+
+
+class Brewer(object):
+    """Encapsulates a nice sequence of colors.
+
+    Shades of blue that look good in color and can be distinguished
+    in grayscale (up to a point).
+    
+    Borrowed from http://colorbrewer2.org/
+    """
+    color_iter = None
+
+    colors = ['#081D58',
+              '#253494',
+              '#225EA8',
+              '#1D91C0',
+              '#41B6C4',
+              '#7FCDBB',
+              '#C7E9B4',
+              '#EDF8B1',
+              '#FFFFD9']
+
+    # lists that indicate which colors to use depending on how many are used
+    which_colors = [[],
+                    [1],
+                    [1, 3],
+                    [0, 2, 4],
+                    [0, 2, 4, 6],
+                    [0, 2, 3, 5, 6],
+                    [0, 2, 3, 4, 5, 6],
+                    [0, 1, 2, 3, 4, 5, 6],
+                    ]
+
+    @classmethod
+    def Colors(cls):
+        """Returns the list of colors.
+        """
+        return cls.colors
+
+    @classmethod
+    def ColorGenerator(cls, n):
+        """Returns an iterator of color strings.
+
+        n: how many colors will be used
+        """
+        for i in cls.which_colors[n]:
+            yield cls.colors[i]
+        raise StopIteration('Ran out of colors in Brewer.ColorGenerator')
+
+    @classmethod
+    def InitializeIter(cls, num):
+        """Initializes the color iterator with the given number of colors."""
+        cls.color_iter = cls.ColorGenerator(num)
+
+    @classmethod
+    def ClearIter(cls):
+        """Sets the color iterator to None."""
+        cls.color_iter = None
+
+    @classmethod
+    def GetIter(cls):
+        """Gets the color iterator."""
+        return cls.color_iter
+
+
+def PrePlot(num=None, rows=1, cols=1):
+    """Takes hints about what's coming.
+
+    num: number of lines that will be plotted
+    """
+    if num:
+        Brewer.InitializeIter(num)
+
+    # TODO: get sharey and sharex working.  probably means switching
+    # to subplots instead of subplot.
+    # also, get rid of the gray background.
+
+    if rows > 1 or cols > 1:
+        pyplot.subplots(rows, cols, sharey=True)
+        global SUBPLOT_ROWS, SUBPLOT_COLS
+        SUBPLOT_ROWS = rows
+        SUBPLOT_COLS = cols
+    
+
+def SubPlot(rows, cols, plot_number):
+    """Configures the number of subplots and changes the current plot.
+
+    rows: int
+    cols: int
+    plot_number: int
+    """
+    pyplot.subplot(rows, cols, plot_number)
+
+
+class InfiniteList(list):
+    """A list that returns the same value for all indices."""
+    def __init__(self, val):
+        """Initializes the list.
+
+        val: value to be stored
+        """
+        list.__init__(self)
+        self.val = val
+
+    def __getitem__(self, index):
+        """Gets the item with the given index.
+
+        index: int
+
+        returns: the stored value
+        """
+        return self.val
+
+
+def Underride(d, **options):
+    """Add key-value pairs to d only if key is not in d.
+
+    If d is None, create a new dictionary.
+
+    d: dictionary
+    options: keyword args to add to d
+    """
+    if d is None:
+        d = {}
+
+    for key, val in options.iteritems():
+        d.setdefault(key, val)
+
+    return d
+
+
+def Clf():
+    """Clears the figure and any hints that have been set."""
+    Brewer.ClearIter()
+    pyplot.clf()
+    
+
+def Figure(**options):
+    """Sets options for the current figure."""
+    Underride(options, figsize=(6, 8))
+    pyplot.figure(**options)
+    
+
+def Plot(xs, ys, style='', **options):
+    """Plots a line.
+
+    Args:
+      xs: sequence of x values
+      ys: sequence of y values
+      style: style string passed along to pyplot.plot
+      options: keyword args passed to pyplot.plot
+    """
+    color_iter = Brewer.GetIter()
+
+    if color_iter:
+        try:
+            options = Underride(options, color=color_iter.next())
+        except StopIteration:
+            print 'Warning: Brewer ran out of colors.'
+            Brewer.ClearIter()
+        
+    options = Underride(options, linewidth=3, alpha=0.8)
+    pyplot.plot(xs, ys, style, **options)
+
+
+def Scatter(xs, ys, **options):
+    """Makes a scatter plot.
+
+    xs: x values
+    ys: y values
+    options: options passed to pyplot.scatter
+    """
+    options = Underride(options, color='blue', alpha=0.2, 
+                        s=30, edgecolors='none')
+    pyplot.scatter(xs, ys, **options)
+
+
+def Pmf(pmf, **options):
+    """Plots a Pmf or Hist as a line.
+
+    Args:
+      pmf: Hist or Pmf object
+      options: keyword args passed to pyplot.plot
+    """
+    xs, ps = pmf.Render()
+    if pmf.name:
+        options = Underride(options, label=pmf.name)
+    Plot(xs, ps, **options)
+
+
+def Pmfs(pmfs, **options):
+    """Plots a sequence of PMFs.
+
+    Options are passed along for all PMFs.  If you want different
+    options for each pmf, make multiple calls to Pmf.
+    
+    Args:
+      pmfs: sequence of PMF objects
+      options: keyword args passed to pyplot.plot
+    """
+    for pmf in pmfs:
+        Pmf(pmf, **options)
+
+
+def Hist(hist, **options):
+    """Plots a Pmf or Hist with a bar plot.
+
+    The default width of the bars is based on the minimum difference
+    between values in the Hist.  If that's too small, you can override
+    it by providing a width keyword argument, in the same units
+    as the values.
+
+    Args:
+      hist: Hist or Pmf object
+      options: keyword args passed to pyplot.bar
+    """
+    # find the minimum distance between adjacent values
+    xs, fs = hist.Render()
+    width = min(Diff(xs))
+
+    if hist.name:
+        options = Underride(options, label=hist.name)
+
+    options = Underride(options, 
+                        align='center',
+                        linewidth=0,
+                        width=width)
+
+    pyplot.bar(xs, fs, **options)
+
+
+def Hists(hists, **options):
+    """Plots two histograms as interleaved bar plots.
+
+    Options are passed along for all PMFs.  If you want different
+    options for each pmf, make multiple calls to Pmf.
+
+    Args:
+      hists: list of two Hist or Pmf objects
+      options: keyword args passed to pyplot.plot
+    """
+    for hist in hists:
+        Hist(hist, **options)
+
+
+def Diff(t):
+    """Compute the differences between adjacent elements in a sequence.
+
+    Args:
+        t: sequence of number
+
+    Returns:
+        sequence of differences (length one less than t)
+    """
+    diffs = [t[i+1] - t[i] for i in range(len(t)-1)]
+    return diffs
+
+
+def Cdf(cdf, complement=False, transform=None, **options):
+    """Plots a CDF as a line.
+
+    Args:
+      cdf: Cdf object
+      complement: boolean, whether to plot the complementary CDF
+      transform: string, one of 'exponential', 'pareto', 'weibull', 'gumbel'
+      options: keyword args passed to pyplot.plot
+
+    Returns:
+      dictionary with the scale options that should be passed to
+      Config, Show or Save.
+    """
+    xs, ps = cdf.Render()
+    scale = dict(xscale='linear', yscale='linear')
+
+    for s in ['xscale', 'yscale']: 
+        if s in options:
+            scale[s] = options.pop(s)
+
+    if transform == 'exponential':
+        complement = True
+        scale['yscale'] = 'log'
+
+    if transform == 'pareto':
+        complement = True
+        scale['yscale'] = 'log'
+        scale['xscale'] = 'log'
+
+    if complement:
+        ps = [1.0-p for p in ps]
+
+    if transform == 'weibull':
+        xs.pop()
+        ps.pop()
+        ps = [-math.log(1.0-p) for p in ps]
+        scale['xscale'] = 'log'
+        scale['yscale'] = 'log'
+
+    if transform == 'gumbel':
+        xs.pop(0)
+        ps.pop(0)
+        ps = [-math.log(p) for p in ps]
+        scale['yscale'] = 'log'
+
+    if cdf.name:
+        options = Underride(options, label=cdf.name)
+
+    Plot(xs, ps, **options)
+    return scale
+
+
+def Cdfs(cdfs, complement=False, transform=None, **options):
+    """Plots a sequence of CDFs.
+    
+    cdfs: sequence of CDF objects
+    complement: boolean, whether to plot the complementary CDF
+    transform: string, one of 'exponential', 'pareto', 'weibull', 'gumbel'
+    options: keyword args passed to pyplot.plot
+    """
+    for cdf in cdfs:
+        Cdf(cdf, complement, transform, **options)
+
+
+def Contour(obj, pcolor=False, contour=True, imshow=False, **options):
+    """Makes a contour plot.
+    
+    d: map from (x, y) to z, or object that provides GetDict
+    pcolor: boolean, whether to make a pseudocolor plot
+    contour: boolean, whether to make a contour plot
+    imshow: boolean, whether to use pyplot.imshow
+    options: keyword args passed to pyplot.pcolor and/or pyplot.contour
+    """
+    try:
+        d = obj.GetDict()
+    except AttributeError:
+        d = obj
+
+    Underride(options, linewidth=3, cmap=matplotlib.cm.Blues)
+
+    xs, ys = zip(*d.iterkeys())
+    xs = sorted(set(xs))
+    ys = sorted(set(ys))
+
+    X, Y = np.meshgrid(xs, ys)
+    func = lambda x, y: d.get((x, y), 0)
+    func = np.vectorize(func)
+    Z = func(X, Y)
+
+    x_formatter = matplotlib.ticker.ScalarFormatter(useOffset=False)
+    axes = pyplot.gca()
+    axes.xaxis.set_major_formatter(x_formatter)
+
+    if pcolor:
+        pyplot.pcolormesh(X, Y, Z, **options)
+    if contour:
+        cs = pyplot.contour(X, Y, Z, **options)
+        pyplot.clabel(cs, inline=1, fontsize=10)
+    if imshow:
+        extent = xs[0], xs[-1], ys[0], ys[-1]
+        pyplot.imshow(Z, extent=extent, **options)
+        
+
+def Pcolor(xs, ys, zs, pcolor=True, contour=False, **options):
+    """Makes a pseudocolor plot.
+    
+    xs:
+    ys:
+    zs:
+    pcolor: boolean, whether to make a pseudocolor plot
+    contour: boolean, whether to make a contour plot
+    options: keyword args passed to pyplot.pcolor and/or pyplot.contour
+    """
+    Underride(options, linewidth=3, cmap=matplotlib.cm.Blues)
+
+    X, Y = np.meshgrid(xs, ys)
+    Z = zs
+
+    x_formatter = matplotlib.ticker.ScalarFormatter(useOffset=False)
+    axes = pyplot.gca()
+    axes.xaxis.set_major_formatter(x_formatter)
+
+    if pcolor:
+        pyplot.pcolormesh(X, Y, Z, **options)
+
+    if contour:
+        cs = pyplot.contour(X, Y, Z, **options)
+        pyplot.clabel(cs, inline=1, fontsize=10)
+        
+
+def Config(**options):
+    """Configures the plot.
+
+    Pulls options out of the option dictionary and passes them to
+    the corresponding pyplot functions.
+    """
+    names = ['title', 'xlabel', 'ylabel', 'xscale', 'yscale',
+             'xticks', 'yticks', 'axis']
+
+    for name in names:
+        if name in options:
+            getattr(pyplot, name)(options[name])
+
+    loc = options.get('loc', 0)
+    legend = options.get('legend', True)
+    if legend:
+        pyplot.legend(loc=loc)
+
+
+def Show(**options):
+    """Shows the plot.
+
+    For options, see Config.
+
+    options: keyword args used to invoke various pyplot functions
+    """
+    # TODO: figure out how to show more than one plot
+    Config(**options)
+    pyplot.show()
+
+
+def Save(root=None, formats=None, **options):
+    """Saves the plot in the given formats.
+
+    For options, see Config.
+
+    Args:
+      root: string filename root
+      formats: list of string formats
+      options: keyword args used to invoke various pyplot functions
+    """
+    Config(**options)
+
+    if formats is None:
+        formats = ['pdf', 'eps']
+
+    if root:
+        for fmt in formats:
+            SaveFormat(root, fmt)
+    Clf()
+
+
+def SaveFormat(root, fmt='eps'):
+    """Writes the current figure to a file in the given format.
+
+    Args:
+      root: string filename root
+      fmt: string format
+    """
+    filename = '%s.%s' % (root, fmt)
+    print 'Writing', filename
+    pyplot.savefig(filename, format=fmt, dpi=300)
+
+
+# provide aliases for calling functons with lower-case names
+preplot = PrePlot
+subplot = SubPlot
+clf = Clf
+figure = Figure
+plot = Plot
+scatter = Scatter
+pmf = Pmf
+pmfs = Pmfs
+hist = Hist
+hists = Hists
+diff = Diff
+cdf = Cdf
+cdfs = Cdfs
+contour = Contour
+pcolor = Pcolor
+config = Config
+show = Show
+save = Save
+
+
+def main():
+    color_iter = Brewer.ColorGenerator(7)
+    for color in color_iter:
+        print color
+
+if __name__ == '__main__':
+    main()