diff options
Diffstat (limited to 'src/xz')
| -rw-r--r-- | src/xz/hardware.c | 43 | ||||
| -rw-r--r-- | src/xz/xz.1 | 21 |
2 files changed, 46 insertions, 18 deletions
diff --git a/src/xz/hardware.c b/src/xz/hardware.c index d91b4cee..74742fce 100644 --- a/src/xz/hardware.c +++ b/src/xz/hardware.c @@ -21,6 +21,9 @@ static uint32_t threadlimit; /// Memory usage limit static uint64_t memlimit; +/// Total amount of physical RAM +static uint64_t total_ram; + extern void hardware_threadlimit_set(uint32_t new_threadlimit) @@ -48,11 +51,27 @@ hardware_threadlimit_get(void) extern void hardware_memlimit_set(uint64_t new_memlimit) { - if (new_memlimit == 0) { - // The default is 40 % of total installed physical RAM. - hardware_memlimit_set_percentage(40); - } else { + if (new_memlimit != 0) { memlimit = new_memlimit; + } else { + // The default depends on the amount of RAM but so that + // on "low-memory" systems the relative limit is higher + // to make it more likely that files created with "xz -9" + // will still decompress without overriding the limit + // manually. + // + // If 40 % of RAM is 80 MiB or more, use 40 % of RAM as + // the limit. + memlimit = 40 * total_ram / 100; + if (memlimit < UINT64_C(80) * 1024 * 1024) { + // If 80 % of RAM is less than 80 MiB, + // use 80 % of RAM as the limit. + memlimit = 80 * total_ram / 100; + if (memlimit > UINT64_C(80) * 1024 * 1024) { + // Otherwise use 80 MiB as the limit. + memlimit = UINT64_C(80) * 1024 * 1024; + } + } } return; @@ -65,14 +84,7 @@ hardware_memlimit_set_percentage(uint32_t percentage) assert(percentage > 0); assert(percentage <= 100); - uint64_t mem = lzma_physmem(); - - // If we cannot determine the amount of RAM, use the assumption - // defined by the configure script. - if (mem == 0) - mem = (uint64_t)(ASSUME_RAM) * 1024 * 1024; - - memlimit = percentage * mem / 100; + memlimit = percentage * total_ram / 100; return; } @@ -87,6 +99,13 @@ hardware_memlimit_get(void) 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; + + // Set the defaults. hardware_memlimit_set(0); hardware_threadlimit_set(0); return; diff --git a/src/xz/xz.1 b/src/xz/xz.1 index 9dc354a0..aba0a693 100644 --- a/src/xz/xz.1 +++ b/src/xz/xz.1 @@ -5,7 +5,7 @@ .\" This file has been put into the public domain. .\" You can do whatever you want with this file. .\" -.TH XZ 1 "2010-01-15" "Tukaani" "XZ Utils" +.TH XZ 1 "2010-03-07" "Tukaani" "XZ Utils" .SH NAME xz, unxz, xzcat, lzma, unlzma, lzcat \- Compress or decompress .xz and .lzma files .SH SYNOPSIS @@ -195,9 +195,16 @@ is several gigabytes. .PP To prevent uncomfortable surprises caused by huge memory usage, .B xz -has a built-in memory usage limiter. The default limit is 40 % of total -physical RAM. While operating systems provide ways to limit the memory usage -of processes, relying on it wasn't deemed to be flexible enough. +has a built-in memory usage limiter. While some operating systems provide +ways to limit the memory usage of processes, relying on it wasn't deemed +to be flexible enough. The default limit depends on the total amount of +physical RAM: +.IP \(bu 3 +If 40\ % of RAM is at least 80 MiB, 40\ % of RAM is used as the limit. +.IP \(bu 3 +If 80\ % of RAM is over 80 MiB, 80 MiB is used as the limit. +.IP \(bu 3 +Otherwise 80\ % of RAM is used as the limit. .PP When compressing, if the selected compression settings exceed the memory usage limit, the settings are automatically adjusted downwards and a notice @@ -588,9 +595,11 @@ can be specified as a percentage of physical RAM. Example: .IP \(bu 3 The .I limit -can be reset back to its default value (currently 40 % of physical RAM) -by setting it to +can be reset back to its default value by setting it to .BR 0 . +See the section +.B "Memory usage" +for how the default limit is defined. .IP \(bu 3 The memory usage limiting can be effectively disabled by setting .I limit |