€•¥A      Œsphinx.addnodes”Œdocument”“”)”}”(Œ	rawsource”Œ ”Œchildren”]”(Œtranslations”ŒLanguagesNode”“”)”}”(hhh]”(h Œpending_xref”“”)”}”(hhh]”Œdocutils.nodes”ŒText”“”ŒChinese (Simplified)”…””}”Œparent”hsbaŒ
attributes”}”(Œids”]”Œclasses”]”Œnames”]”Œdupnames”]”Œbackrefs”]”Œ	refdomain”Œstd”Œreftype”Œdoc”Œ	reftarget”Œ /translations/zh_CN/block/ioprio”Œmodname”NŒ	classname”NŒrefexplicit”ˆuŒtagname”hhhubh)”}”(hhh]”hŒChinese (Traditional)”…””}”hh2sbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ /translations/zh_TW/block/ioprio”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒItalian”…””}”hhFsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ /translations/it_IT/block/ioprio”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒJapanese”…””}”hhZsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ /translations/ja_JP/block/ioprio”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒKorean”…””}”hhnsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ /translations/ko_KR/block/ioprio”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒPortuguese (Brazilian)”…””}”hh‚sbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ /translations/pt_BR/block/ioprio”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒSpanish”…””}”hh–sbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ /translations/sp_SP/block/ioprio”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubeh}”(h]”h ]”h"]”h$]”h&]”Œcurrent_language”ŒEnglish”uh1h
hhŒ	_document”hŒsource”NŒline”NubhŒsection”“”)”}”(hhh]”(hŒtitle”“”)”}”(hŒBlock io priorities”h]”hŒBlock io priorities”…””}”(hh¼h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hºhh·h²hh³Œ:/var/lib/git/docbuild/linux/Documentation/block/ioprio.rst”h´Kubh¶)”}”(hhh]”(h»)”}”(hŒIntro”h]”hŒIntro”…””}”(hhÎh²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hºhhËh²hh³hÊh´KubhŒ	paragraph”“”)”}”(hŒñThe io priority feature enables users to io nice processes or process groups,
similar to what has been possible with cpu scheduling for ages. Support for io
priorities is io scheduler dependent and currently supported by bfq and
mq-deadline.”h]”hŒñThe io priority feature enables users to io nice processes or process groups,
similar to what has been possible with cpu scheduling for ages. Support for io
priorities is io scheduler dependent and currently supported by bfq and
mq-deadline.”…””}”(hhÞh²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´K	hhËh²hubeh}”(h]”Œintro”ah ]”h"]”Œintro”ah$]”h&]”uh1hµhh·h²hh³hÊh´Kubh¶)”}”(hhh]”(h»)”}”(hŒScheduling classes”h]”hŒScheduling classes”…””}”(hh÷h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hºhhôh²hh³hÊh´KubhÝ)”}”(hŒqThree generic scheduling classes are implemented for io priorities that
determine how io is served for a process.”h]”hŒqThree generic scheduling classes are implemented for io priorities that
determine how io is served for a process.”…””}”(hj  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´Khhôh²hubhÝ)”}”(hX!  IOPRIO_CLASS_RT: This is the realtime io class. This scheduling class is given
higher priority than any other in the system, processes from this class are
given first access to the disk every time. Thus it needs to be used with some
care, one io RT process can starve the entire system. Within the RT class,
there are 8 levels of class data that determine exactly how much time this
process needs the disk for on each service. In the future this might change
to be more directly mappable to performance, by passing in a wanted data
rate instead.”h]”hX!  IOPRIO_CLASS_RT: This is the realtime io class. This scheduling class is given
higher priority than any other in the system, processes from this class are
given first access to the disk every time. Thus it needs to be used with some
care, one io RT process can starve the entire system. Within the RT class,
there are 8 levels of class data that determine exactly how much time this
process needs the disk for on each service. In the future this might change
to be more directly mappable to performance, by passing in a wanted data
rate instead.”…””}”(hj  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´Khhôh²hubhÝ)”}”(hX²  IOPRIO_CLASS_BE: This is the best-effort scheduling class, which is the default
for any process that hasn't set a specific io priority. The class data
determines how much io bandwidth the process will get, it's directly mappable
to the cpu nice levels just more coarsely implemented. 0 is the highest
BE prio level, 7 is the lowest. The mapping between cpu nice level and io
nice level is determined as: io_nice = (cpu_nice + 20) / 5.”h]”hX¶  IOPRIO_CLASS_BE: This is the best-effort scheduling class, which is the default
for any process that hasnâ€™t set a specific io priority. The class data
determines how much io bandwidth the process will get, itâ€™s directly mappable
to the cpu nice levels just more coarsely implemented. 0 is the highest
BE prio level, 7 is the lowest. The mapping between cpu nice level and io
nice level is determined as: io_nice = (cpu_nice + 20) / 5.”…””}”(hj!  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´Khhôh²hubhÝ)”}”(hŒÍIOPRIO_CLASS_IDLE: This is the idle scheduling class, processes running at this
level only get io time when no one else needs the disk. The idle class has no
class data, since it doesn't really apply here.”h]”hŒÏIOPRIO_CLASS_IDLE: This is the idle scheduling class, processes running at this
level only get io time when no one else needs the disk. The idle class has no
class data, since it doesnâ€™t really apply here.”…””}”(hj/  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´K$hhôh²hubeh}”(h]”Œscheduling-classes”ah ]”h"]”Œscheduling classes”ah$]”h&]”uh1hµhh·h²hh³hÊh´Kubh¶)”}”(hhh]”(h»)”}”(hŒTools”h]”hŒTools”…””}”(hjH  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hºhjE  h²hh³hÊh´K)ubhÝ)”}”(hŒ+See below for a sample ionice tool. Usage::”h]”hŒ*See below for a sample ionice tool. Usage:”…””}”(hjV  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´K+hjE  h²hubhŒliteral_block”“”)”}”(hŒ$# ionice -c<class> -n<level> -p<pid>”h]”hŒ$# ionice -c<class> -n<level> -p<pid>”…””}”hjf  sbah}”(h]”h ]”h"]”h$]”h&]”Œ	xml:space”Œpreserve”uh1jd  h³hÊh´K-hjE  h²hubhÝ)”}”(hŒIf pid isn't given, the current process is assumed. IO priority settings
are inherited on fork, so you can use ionice to start the process at a given
level::”h]”hŒžIf pid isnâ€™t given, the current process is assumed. IO priority settings
are inherited on fork, so you can use ionice to start the process at a given
level:”…””}”(hjv  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´K/hjE  h²hubje  )”}”(hŒ# ionice -c2 -n0 /bin/ls”h]”hŒ# ionice -c2 -n0 /bin/ls”…””}”hj„  sbah}”(h]”h ]”h"]”h$]”h&]”jt  ju  uh1jd  h³hÊh´K3hjE  h²hubhÝ)”}”(hŒ~will run ls at the best-effort scheduling class at the highest priority.
For a running process, you can give the pid instead::”h]”hŒ}will run ls at the best-effort scheduling class at the highest priority.
For a running process, you can give the pid instead:”…””}”(hj’  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´K5hjE  h²hubje  )”}”(hŒ# ionice -c1 -n2 -p100”h]”hŒ# ionice -c1 -n2 -p100”…””}”hj   sbah}”(h]”h ]”h"]”h$]”h&]”jt  ju  uh1jd  h³hÊh´K8hjE  h²hubhÝ)”}”(hŒKwill change pid 100 to run at the realtime scheduling class, at priority 2.”h]”hŒKwill change pid 100 to run at the realtime scheduling class, at priority 2.”…””}”(hj®  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´K:hjE  h²hubhÝ)”}”(hŒionice.c tool::”h]”hŒionice.c tool:”…””}”(hj¼  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´K<hjE  h²hubje  )”}”(hX  #include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <getopt.h>
#include <unistd.h>
#include <sys/ptrace.h>
#include <asm/unistd.h>

extern int sys_ioprio_set(int, int, int);
extern int sys_ioprio_get(int, int);

#if defined(__i386__)
#define __NR_ioprio_set               289
#define __NR_ioprio_get               290
#elif defined(__ppc__)
#define __NR_ioprio_set               273
#define __NR_ioprio_get               274
#elif defined(__x86_64__)
#define __NR_ioprio_set               251
#define __NR_ioprio_get               252
#else
#error "Unsupported arch"
#endif

static inline int ioprio_set(int which, int who, int ioprio)
{
      return syscall(__NR_ioprio_set, which, who, ioprio);
}

static inline int ioprio_get(int which, int who)
{
      return syscall(__NR_ioprio_get, which, who);
}

enum {
      IOPRIO_CLASS_NONE,
      IOPRIO_CLASS_RT,
      IOPRIO_CLASS_BE,
      IOPRIO_CLASS_IDLE,
};

enum {
      IOPRIO_WHO_PROCESS = 1,
      IOPRIO_WHO_PGRP,
      IOPRIO_WHO_USER,
};

#define IOPRIO_CLASS_SHIFT    13

const char *to_prio[] = { "none", "realtime", "best-effort", "idle", };

int main(int argc, char *argv[])
{
      int ioprio = 4, set = 0, ioprio_class = IOPRIO_CLASS_BE;
      int c, pid = 0;

      while ((c = getopt(argc, argv, "+n:c:p:")) != EOF) {
              switch (c) {
              case 'n':
                      ioprio = strtol(optarg, NULL, 10);
                      set = 1;
                      break;
              case 'c':
                      ioprio_class = strtol(optarg, NULL, 10);
                      set = 1;
                      break;
              case 'p':
                      pid = strtol(optarg, NULL, 10);
                      break;
              }
      }

      switch (ioprio_class) {
              case IOPRIO_CLASS_NONE:
                      ioprio_class = IOPRIO_CLASS_BE;
                      break;
              case IOPRIO_CLASS_RT:
              case IOPRIO_CLASS_BE:
                      break;
              case IOPRIO_CLASS_IDLE:
                      ioprio = 7;
                      break;
              default:
                      printf("bad prio class %d\n", ioprio_class);
                      return 1;
      }

      if (!set) {
              if (!pid && argv[optind])
                      pid = strtol(argv[optind], NULL, 10);

              ioprio = ioprio_get(IOPRIO_WHO_PROCESS, pid);

              printf("pid=%d, %d\n", pid, ioprio);

              if (ioprio == -1)
                      perror("ioprio_get");
              else {
                      ioprio_class = ioprio >> IOPRIO_CLASS_SHIFT;
                      ioprio = ioprio & 0xff;
                      printf("%s: prio %d\n", to_prio[ioprio_class], ioprio);
              }
      } else {
              if (ioprio_set(IOPRIO_WHO_PROCESS, pid, ioprio | ioprio_class << IOPRIO_CLASS_SHIFT) == -1) {
                      perror("ioprio_set");
                      return 1;
              }

              if (argv[optind])
                      execvp(argv[optind], &argv[optind]);
      }

      return 0;
}”h]”hX  #include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <getopt.h>
#include <unistd.h>
#include <sys/ptrace.h>
#include <asm/unistd.h>

extern int sys_ioprio_set(int, int, int);
extern int sys_ioprio_get(int, int);

#if defined(__i386__)
#define __NR_ioprio_set               289
#define __NR_ioprio_get               290
#elif defined(__ppc__)
#define __NR_ioprio_set               273
#define __NR_ioprio_get               274
#elif defined(__x86_64__)
#define __NR_ioprio_set               251
#define __NR_ioprio_get               252
#else
#error "Unsupported arch"
#endif

static inline int ioprio_set(int which, int who, int ioprio)
{
      return syscall(__NR_ioprio_set, which, who, ioprio);
}

static inline int ioprio_get(int which, int who)
{
      return syscall(__NR_ioprio_get, which, who);
}

enum {
      IOPRIO_CLASS_NONE,
      IOPRIO_CLASS_RT,
      IOPRIO_CLASS_BE,
      IOPRIO_CLASS_IDLE,
};

enum {
      IOPRIO_WHO_PROCESS = 1,
      IOPRIO_WHO_PGRP,
      IOPRIO_WHO_USER,
};

#define IOPRIO_CLASS_SHIFT    13

const char *to_prio[] = { "none", "realtime", "best-effort", "idle", };

int main(int argc, char *argv[])
{
      int ioprio = 4, set = 0, ioprio_class = IOPRIO_CLASS_BE;
      int c, pid = 0;

      while ((c = getopt(argc, argv, "+n:c:p:")) != EOF) {
              switch (c) {
              case 'n':
                      ioprio = strtol(optarg, NULL, 10);
                      set = 1;
                      break;
              case 'c':
                      ioprio_class = strtol(optarg, NULL, 10);
                      set = 1;
                      break;
              case 'p':
                      pid = strtol(optarg, NULL, 10);
                      break;
              }
      }

      switch (ioprio_class) {
              case IOPRIO_CLASS_NONE:
                      ioprio_class = IOPRIO_CLASS_BE;
                      break;
              case IOPRIO_CLASS_RT:
              case IOPRIO_CLASS_BE:
                      break;
              case IOPRIO_CLASS_IDLE:
                      ioprio = 7;
                      break;
              default:
                      printf("bad prio class %d\n", ioprio_class);
                      return 1;
      }

      if (!set) {
              if (!pid && argv[optind])
                      pid = strtol(argv[optind], NULL, 10);

              ioprio = ioprio_get(IOPRIO_WHO_PROCESS, pid);

              printf("pid=%d, %d\n", pid, ioprio);

              if (ioprio == -1)
                      perror("ioprio_get");
              else {
                      ioprio_class = ioprio >> IOPRIO_CLASS_SHIFT;
                      ioprio = ioprio & 0xff;
                      printf("%s: prio %d\n", to_prio[ioprio_class], ioprio);
              }
      } else {
              if (ioprio_set(IOPRIO_WHO_PROCESS, pid, ioprio | ioprio_class << IOPRIO_CLASS_SHIFT) == -1) {
                      perror("ioprio_set");
                      return 1;
              }

              if (argv[optind])
                      execvp(argv[optind], &argv[optind]);
      }

      return 0;
}”…””}”hjÊ  sbah}”(h]”h ]”h"]”h$]”h&]”jt  ju  uh1jd  h³hÊh´K>hjE  h²hubhÝ)”}”(hŒ1March 11 2005, Jens Axboe <jens.axboe@oracle.com>”h]”(hŒMarch 11 2005, Jens Axboe <”…””}”(hjØ  h²hh³Nh´NubhŒ	reference”“”)”}”(hŒjens.axboe@oracle.com”h]”hŒjens.axboe@oracle.com”…””}”(hjâ  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”Œrefuri”Œmailto:jens.axboe@oracle.com”uh1jà  hjØ  ubhŒ>”…””}”(hjØ  h²hh³Nh´Nubeh}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´K²hjE  h²hubeh}”(h]”Œtools”ah ]”h"]”Œtools”ah$]”h&]”uh1hµhh·h²hh³hÊh´K)ubeh}”(h]”Œblock-io-priorities”ah ]”h"]”Œblock io priorities”ah$]”h&]”uh1hµhhh²hh³hÊh´Kubeh}”(h]”h ]”h"]”h$]”h&]”Œsource”hÊuh1hŒcurrent_source”NŒcurrent_line”NŒsettings”Œdocutils.frontend”ŒValues”“”)”}”(hºNŒ	generator”NŒ	datestamp”NŒsource_link”NŒ
source_url”NŒtoc_backlinks”Œentry”Œfootnote_backlinks”KŒsectnum_xform”KŒstrip_comments”NŒstrip_elements_with_classes”NŒstrip_classes”NŒreport_level”KŒ
halt_level”KŒexit_status_level”KŒdebug”NŒwarning_stream”NŒ	traceback”ˆŒinput_encoding”Œ	utf-8-sig”Œinput_encoding_error_handler”Œstrict”Œoutput_encoding”Œutf-8”Œoutput_encoding_error_handler”j/  Œerror_encoding”Œutf-8”Œerror_encoding_error_handler”Œbackslashreplace”Œlanguage_code”Œen”Œrecord_dependencies”NŒconfig”NŒ	id_prefix”hŒauto_id_prefix”Œid”Œdump_settings”NŒdump_internals”NŒdump_transforms”NŒdump_pseudo_xml”NŒexpose_internals”NŒstrict_visitor”NŒ_disable_config”NŒ_source”hÊŒ_destination”NŒ_config_files”]”Œ7/var/lib/git/docbuild/linux/Documentation/docutils.conf”aŒfile_insertion_enabled”ˆŒraw_enabled”KŒline_length_limit”M'Œpep_references”NŒpep_base_url”Œhttps://peps.python.org/”Œpep_file_url_template”Œpep-%04d”Œrfc_references”NŒrfc_base_url”Œ&https://datatracker.ietf.org/doc/html/”Œ	tab_width”KŒtrim_footnote_reference_space”‰Œsyntax_highlight”Œlong”Œsmart_quotes”ˆŒsmartquotes_locales”]”Œcharacter_level_inline_markup”‰Œdoctitle_xform”‰Œdocinfo_xform”KŒsectsubtitle_xform”‰Œimage_loading”Œlink”Œembed_stylesheet”‰Œcloak_email_addresses”ˆŒsection_self_link”‰Œenv”NubŒreporter”NŒindirect_targets”]”Œsubstitution_defs”}”Œsubstitution_names”}”Œrefnames”}”Œrefids”}”Œnameids”}”(j	  j  hñhîjB  j?  j  jþ  uŒ	nametypes”}”(j	  ‰hñ‰jB  ‰j  ‰uh}”(j  h·hîhËj?  hôjþ  jE  uŒfootnote_refs”}”Œcitation_refs”}”Œautofootnotes”]”Œautofootnote_refs”]”Œsymbol_footnotes”]”Œsymbol_footnote_refs”]”Œ	footnotes”]”Œ	citations”]”Œautofootnote_start”KŒsymbol_footnote_start”K Œ
id_counter”Œcollections”ŒCounter”“”}”…”R”Œparse_messages”]”Œtransform_messages”]”Œtransformer”NŒinclude_log”]”Œ
decoration”Nh²hub.