1 files changed, 338 insertions, 0 deletions
diff --git a/src/xz/hardware.c b/src/xz/hardware.c
new file mode 100644
index 0000000..c694882
--- /dev/null
+++ b/src/xz/hardware.c
@@ -0,0 +1,338 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file       hardware.c
+/// \brief      Detection of available hardware resources
+//
+//  Author:     Lasse Collin
+//
+//  This file has been put into the public domain.
+//  You can do whatever you want with this file.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#include "private.h"
+
+
+/// Maximum number of worker threads. This can be set with
+/// the --threads=NUM command line option.
+static uint32_t threads_max = 1;
+
+/// True when the number of threads is automatically determined based
+/// on the available hardware threads.
+static bool threads_are_automatic = false;
+
+/// If true, then try to use multi-threaded mode (if memlimit allows)
+/// even if only one thread was requested explicitly (-T+1).
+static bool use_mt_mode_with_one_thread = false;
+
+/// Memory usage limit for compression
+static uint64_t memlimit_compress = 0;
+
+/// Memory usage limit for decompression
+static uint64_t memlimit_decompress = 0;
+
+/// Default memory usage for multithreaded modes:
+///
+///   - Default value for --memlimit-compress when automatic number of threads
+///     is used. However, if the limit wouldn't allow even one thread then
+///     the limit is ignored in coder.c and one thread will be used anyway.
+///     This mess is a compromise: we wish to prevent -T0 from using too
+///     many threads but we also don't want xz to give an error due to
+///     a memlimit that the user didn't explicitly set.
+///
+///   - Default value for --memlimit-mt-decompress
+///
+/// This value is calculated in hardware_init() and cannot be changed later.
+static uint64_t memlimit_mt_default;
+
+/// Memory usage limit for multithreaded decompression. This is a soft limit:
+/// if reducing the number of threads to one isn't enough to keep memory
+/// usage below this limit, then one thread is used and this limit is ignored.
+/// memlimit_decompress is still obeyed.
+///
+/// This can be set with --memlimit-mt-decompress. The default value for
+/// this is memlimit_mt_default.
+static uint64_t memlimit_mtdec;
+
+/// Total amount of physical RAM
+static uint64_t total_ram;
+
+
+extern void
+hardware_threads_set(uint32_t n)
+{
+	// Reset these to false first and set them to true when appropriate.
+	threads_are_automatic = false;
+	use_mt_mode_with_one_thread = false;
+
+	if (n == 0) {
+		// Automatic number of threads was requested.
+		// If there is only one hardware thread, multi-threaded
+		// mode will still be used if memory limit allows.
+		threads_are_automatic = true;
+		use_mt_mode_with_one_thread = true;
+
+		// If threading support was enabled at build time,
+		// use the number of available CPU cores. Otherwise
+		// use one thread since disabling threading support
+		// omits lzma_cputhreads() from liblzma.
+#ifdef MYTHREAD_ENABLED
+		threads_max = lzma_cputhreads();
+		if (threads_max == 0)
+			threads_max = 1;
+#else
+		threads_max = 1;
+#endif
+	} else if (n == UINT32_MAX) {
+		use_mt_mode_with_one_thread = true;
+		threads_max = 1;
+	} else {
+		threads_max = n;
+	}
+
+	return;
+}
+
+
+extern uint32_t
+hardware_threads_get(void)
+{
+	return threads_max;
+}
+
+
+extern bool
+hardware_threads_is_mt(void)
+{
+#ifdef MYTHREAD_ENABLED
+	return threads_max > 1 || use_mt_mode_with_one_thread;
+#else
+	return false;
+#endif
+}
+
+
+extern void
+hardware_memlimit_set(uint64_t new_memlimit,
+		bool set_compress, bool set_decompress, bool set_mtdec,
+		bool is_percentage)
+{
+	if (is_percentage) {
+		assert(new_memlimit > 0);
+		assert(new_memlimit <= 100);
+		new_memlimit = (uint32_t)new_memlimit * total_ram / 100;
+	}
+
+	if (set_compress) {
+		memlimit_compress = new_memlimit;
+
+#if SIZE_MAX == UINT32_MAX
+		// FIXME?
+		//
+		// When running a 32-bit xz on a system with a lot of RAM and
+		// using a percentage-based memory limit, the result can be
+		// bigger than the 32-bit address space. Limiting the limit
+		// below SIZE_MAX for compression (not decompression) makes
+		// xz lower the compression settings (or number of threads)
+		// to a level that *might* work. In practice it has worked
+		// when using a 64-bit kernel that gives full 4 GiB address
+		// space to 32-bit programs. In other situations this might
+		// still be too high, like 32-bit kernels that may give much
+		// less than 4 GiB to a single application.
+		//
+		// So this is an ugly hack but I will keep it here while
+		// it does more good than bad.
+		//
+		// Use a value less than SIZE_MAX so that there's some room
+		// for the xz program and so on. Don't use 4000 MiB because
+		// it could look like someone mixed up base-2 and base-10.
+#ifdef __mips__
+		// For MIPS32, due to architectural peculiarities,
+		// the limit is even lower.
+		const uint64_t limit_max = UINT64_C(2000) << 20;
+#else
+		const uint64_t limit_max = UINT64_C(4020) << 20;
+#endif
+
+		// UINT64_MAX is a special case for the string "max" so
+		// that has to be handled specially.
+		if (memlimit_compress != UINT64_MAX
+				&& memlimit_compress > limit_max)
+			memlimit_compress = limit_max;
+#endif
+	}
+
+	if (set_decompress)
+		memlimit_decompress = new_memlimit;
+
+	if (set_mtdec)
+		memlimit_mtdec = new_memlimit;
+
+	return;
+}
+
+
+extern uint64_t
+hardware_memlimit_get(enum operation_mode mode)
+{
+	// 0 is a special value that indicates the default.
+	// It disables the limit in single-threaded mode.
+	//
+	// NOTE: For multithreaded decompression, this is the hard limit
+	// (memlimit_stop). hardware_memlimit_mtdec_get() gives the
+	// soft limit (memlimit_threaded).
+	const uint64_t memlimit = mode == MODE_COMPRESS
+			? memlimit_compress : memlimit_decompress;
+	return memlimit != 0 ? memlimit : UINT64_MAX;
+}
+
+
+extern uint64_t
+hardware_memlimit_mtenc_get(void)
+{
+	return hardware_memlimit_mtenc_is_default()
+			? memlimit_mt_default
+			: hardware_memlimit_get(MODE_COMPRESS);
+}
+
+
+extern bool
+hardware_memlimit_mtenc_is_default(void)
+{
+	return memlimit_compress == 0 && threads_are_automatic;
+}
+
+
+extern uint64_t
+hardware_memlimit_mtdec_get(void)
+{
+	uint64_t m = memlimit_mtdec != 0
+			? memlimit_mtdec
+			: memlimit_mt_default;
+
+	// Cap the value to memlimit_decompress if it has been specified.
+	// This is nice for --info-memory. It wouldn't be needed for liblzma
+	// since it does this anyway.
+	if (memlimit_decompress != 0 && m > memlimit_decompress)
+		m = memlimit_decompress;
+
+	return m;
+}
+
+
+/// Helper for hardware_memlimit_show() to print one human-readable info line.
+static void
+memlimit_show(const char *str, size_t str_columns, uint64_t value)
+{
+	// Calculate the field width so that str will be padded to take
+	// str_columns on the terminal.
+	//
+	// NOTE: If the string is invalid, this will be -1. Using -1 as
+	// the field width is fine here so it's not handled specially.
+	const int fw = tuklib_mbstr_fw(str, (int)(str_columns));
+
+	// The memory usage limit is considered to be disabled if value
+	// is 0 or UINT64_MAX. This might get a bit more complex once there
+	// is threading support. See the comment in hardware_memlimit_get().
+	if (value == 0 || value == UINT64_MAX)
+		printf("  %-*s  %s\n", fw, str, _("Disabled"));
+	else
+		printf("  %-*s  %s MiB (%s B)\n", fw, str,
+				uint64_to_str(round_up_to_mib(value), 0),
+				uint64_to_str(value, 1));
+
+	return;
+}
+
+
+extern void
+hardware_memlimit_show(void)
+{
+	uint32_t cputhreads = 1;
+#ifdef MYTHREAD_ENABLED
+	cputhreads = lzma_cputhreads();
+	if (cputhreads == 0)
+		cputhreads = 1;
+#endif
+
+	if (opt_robot) {
+		printf("%" PRIu64 "\t%" PRIu64 "\t%" PRIu64 "\t%" PRIu64
+				"\t%" PRIu64 "\t%" PRIu32 "\n",
+				total_ram,
+				memlimit_compress,
+				memlimit_decompress,
+				hardware_memlimit_mtdec_get(),
+				memlimit_mt_default,
+				cputhreads);
+	} else {
+		const char *msgs[] = {
+			_("Amount of physical memory (RAM):"),
+			_("Number of processor threads:"),
+			_("Compression:"),
+			_("Decompression:"),
+			_("Multi-threaded decompression:"),
+			_("Default for -T0:"),
+		};
+
+		size_t width_max = 1;
+		for (unsigned i = 0; i < ARRAY_SIZE(msgs); ++i) {
+			size_t w = tuklib_mbstr_width(msgs[i], NULL);
+
+			// When debugging, catch invalid strings with
+			// an assertion. Otherwise fallback to 1 so
+			// that the columns just won't be aligned.
+			assert(w != (size_t)-1);
+			if (w == (size_t)-1)
+				w = 1;
+
+			if (width_max < w)
+				width_max = w;
+		}
+
+		puts(_("Hardware information:"));
+		memlimit_show(msgs[0], width_max, total_ram);
+		printf("  %-*s  %" PRIu32 "\n",
+				tuklib_mbstr_fw(msgs[1], (int)(width_max)),
+				msgs[1], cputhreads);
+
+		putchar('\n');
+		puts(_("Memory usage limits:"));
+		memlimit_show(msgs[2], width_max, memlimit_compress);
+		memlimit_show(msgs[3], width_max, memlimit_decompress);
+		memlimit_show(msgs[4], width_max,
+				hardware_memlimit_mtdec_get());
+		memlimit_show(msgs[5], width_max, memlimit_mt_default);
+	}
+
+	tuklib_exit(E_SUCCESS, E_ERROR, message_verbosity_get() != V_SILENT);
+}
+
+
+extern void
+hardware_init(void)
+{
+	// Get the amount of RAM. If we cannot determine it,
+	// use the assumption defined by the configure script.
+	total_ram = lzma_physmem();
+	if (total_ram == 0)
+		total_ram = (uint64_t)(ASSUME_RAM) * 1024 * 1024;
+
+	// FIXME? There may be better methods to determine the default value.
+	// One Linux-specific suggestion is to use MemAvailable from
+	// /proc/meminfo as the starting point.
+	memlimit_mt_default = total_ram / 4;
+
+#if SIZE_MAX == UINT32_MAX
+	// A too high value may cause 32-bit xz to run out of address space.
+	// Use a conservative maximum value here. A few typical address space
+	// sizes with Linux:
+	//   - x86-64 with 32-bit xz: 4 GiB
+	//   - x86: 3 GiB
+	//   - MIPS32: 2 GiB
+	const size_t mem_ceiling = 1400U << 20;
+	if (memlimit_mt_default > mem_ceiling)
+		memlimit_mt_default = mem_ceiling;
+#endif
+
+	return;
+}