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137 lines
3.4 KiB
C++
137 lines
3.4 KiB
C++
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// Copyright Oliver Kowalke 2009.
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// Distributed under the Boost Software License, Version 1.0.
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// (See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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#define BOOST_PP_LIMIT_MAG 10
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#include <cstdio>
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#include <cstdlib>
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#include <iostream>
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#include <stdexcept>
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#include <boost/assert.hpp>
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#include <boost/bind.hpp>
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#include <boost/config.hpp>
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#include <boost/context/all.hpp>
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#include <boost/preprocessor/repetition/repeat_from_to.hpp>
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#ifndef BOOST_WINDOWS
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#include <ucontext.h>
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#endif
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#include "bind_processor.hpp"
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#include "performance.hpp"
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namespace ctx = boost::ctx;
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#define CALL_UCONTEXT(z,n,unused) \
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::swapcontext( & ucm, & uc);
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#define CALL_FCONTEXT(z,n,unused) \
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ctx::jump_fcontext( & fcm, & fc, 0);
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#ifndef BOOST_WINDOWS
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ucontext_t uc, ucm;
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#endif
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ctx::fcontext_t fc, fcm;
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#ifndef BOOST_WINDOWS
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static void f2()
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{
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while ( true)
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::swapcontext( & uc, & ucm);
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}
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#endif
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static void f1( intptr_t)
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{
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while ( true)
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ctx::jump_fcontext( & fc, & fcm, 0);
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}
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#ifndef BOOST_WINDOWS
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unsigned int test_ucontext()
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{
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cycle_t overhead( get_overhead() );
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std::cout << "overhead for rdtsc == " << overhead << " cycles" << std::endl;
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ctx::stack_allocator alloc;
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::getcontext( & uc);
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uc.uc_stack.ss_sp =
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static_cast< char * >( alloc.allocate(ctx::default_stacksize() ) )
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- ctx::default_stacksize();
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uc.uc_stack.ss_size = ctx::default_stacksize();
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::makecontext( & uc, f2, 0);
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// cache warum-up
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BOOST_PP_REPEAT_FROM_TO( 0, BOOST_PP_LIMIT_MAG, CALL_UCONTEXT, ~)
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cycle_t start( get_cycles() );
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BOOST_PP_REPEAT_FROM_TO( 0, BOOST_PP_LIMIT_MAG, CALL_UCONTEXT, ~)
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cycle_t total( get_cycles() - start);
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// we have two jumps and two measuremt-overheads
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total -= overhead; // overhead of measurement
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total /= BOOST_PP_LIMIT_MAG; // per call
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total /= 2; // 2x jump_to c1->c2 && c2->c1
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return total;
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}
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#endif
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unsigned int test_fcontext()
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{
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cycle_t overhead( get_overhead() );
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std::cout << "overhead for rdtsc == " << overhead << " cycles" << std::endl;
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ctx::stack_allocator alloc;
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fc.fc_stack.base = alloc.allocate(ctx::default_stacksize());
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fc.fc_stack.limit =
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static_cast< char * >( fc.fc_stack.base) - ctx::default_stacksize();
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ctx::make_fcontext( & fc, f1, 0);
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ctx::start_fcontext( & fcm, & fc);
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// cache warum-up
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BOOST_PP_REPEAT_FROM_TO( 0, BOOST_PP_LIMIT_MAG, CALL_FCONTEXT, ~)
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cycle_t start( get_cycles() );
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BOOST_PP_REPEAT_FROM_TO( 0, BOOST_PP_LIMIT_MAG, CALL_FCONTEXT, ~)
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cycle_t total( get_cycles() - start);
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// we have two jumps and two measuremt-overheads
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total -= overhead; // overhead of measurement
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total /= BOOST_PP_LIMIT_MAG; // per call
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total /= 2; // 2x jump_to c1->c2 && c2->c1
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return total;
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}
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int main( int argc, char * argv[])
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{
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try
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{
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bind_to_processor( 0);
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unsigned int res = test_fcontext();
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std::cout << "fcontext: average of " << res << " cycles per switch" << std::endl;
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#ifndef BOOST_WINDOWS
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res = test_ucontext();
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std::cout << "ucontext: average of " << res << " cycles per switch" << std::endl;
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#endif
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return EXIT_SUCCESS;
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}
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catch ( std::exception const& e)
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{ std::cerr << "exception: " << e.what() << std::endl; }
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catch (...)
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{ std::cerr << "unhandled exception" << std::endl; }
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return EXIT_FAILURE;
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}
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#undef CALL_FCONTEXT
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#undef CALL_UCONTEXT
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