diff options
Diffstat (limited to 'src/xz/hardware.c')
| -rw-r--r-- | src/xz/hardware.c | 60 |
1 files changed, 55 insertions, 5 deletions
diff --git a/src/xz/hardware.c b/src/xz/hardware.c index 0ad8c658..d45d6ade 100644 --- a/src/xz/hardware.c +++ b/src/xz/hardware.c @@ -18,10 +18,26 @@ static uint32_t threads_max = 1; /// Memory usage limit for compression -static uint64_t memlimit_compress; +static uint64_t memlimit_compress = 0; /// Memory usage limit for decompression -static uint64_t memlimit_decompress; +static uint64_t memlimit_decompress = 0; + +/// Default memory usage for multithreaded modes: +/// +/// - Default value for --memlimit-mt-decompress +/// +/// This value is caluclated 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; @@ -60,7 +76,8 @@ hardware_threads_get(void) extern void hardware_memlimit_set(uint64_t new_memlimit, - bool set_compress, bool set_decompress, bool is_percentage) + bool set_compress, bool set_decompress, bool set_mtdec, + bool is_percentage) { if (is_percentage) { assert(new_memlimit > 0); @@ -110,6 +127,9 @@ hardware_memlimit_set(uint64_t new_memlimit, if (set_decompress) memlimit_decompress = new_memlimit; + if (set_mtdec) + memlimit_mtdec = new_memlimit; + return; } @@ -132,6 +152,23 @@ hardware_memlimit_get(enum operation_mode mode) } +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) @@ -203,7 +240,20 @@ hardware_init(void) if (total_ram == 0) total_ram = (uint64_t)(ASSUME_RAM) * 1024 * 1024; - // Set the defaults. - hardware_memlimit_set(0, true, true, false); + // 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; + + // 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 = SIZE_MAX / 3; // About 1365 GiB on 32-bit + if (memlimit_mt_default > mem_ceiling) + memlimit_mt_default = mem_ceiling; + return; } |