Re: [Qemu-devel] [PATCH v2] Add option to mlock qemu and guest memory

[Satoru Moriya]

Ping.

Can anyone else review this patch?

Regards,
Satoru

On 03/12/2013 05:40 AM, Paolo Bonzini wrote:
> Il 14/02/2013 21:21, Satoru Moriya ha scritto:
>> We have some plans to migrate legacy enterprise systems which require 
>> low latency (10 msec order) to kvm virtualized environment. In our 
>> usecase, the system runs with other untrusted guests and so locking 
>> memory which is used by the system is needed to avoid latency impacts 
>> from other guests' memory activity.
>>
>> ChangeLog:
>> v2
>>  - Change the option name from -mlock to -realtime mlock=on|off
>>  - Rebase qemu version 1.3.91
>>  - Update patch description
>>
>> ---
>> In certain scenario, latency induced by paging is significant and 
>> memory locking is needed. Also, in the scenario with untrusted 
>> guests, latency improvement due to mlock is desired.
>>
>> This patch introduces a following new option to mlock guest and qemu 
>> memory:
>>
>> -realtime mlock=on|off
>>
>> Signed-off-by: Satoru Moriya <address@hidden>
> 
> Reviewed-by: Paolo Bonzini <address@hidden>
> 
> As a follow up it would be nice to move -mem-prealloc/-mem-path under 
> -realtime as well.
> 
> Paolo
> 
>> ---
>>  include/sysemu/os-posix.h |  1 +
>>  include/sysemu/os-win32.h |  1 +
>>  os-posix.c                |  8 ++++++++
>>  qemu-options.hx           | 13 +++++++++++++
>>  vl.c                      | 31 +++++++++++++++++++++++++++++++
>>  5 files changed, 54 insertions(+)
>>
>> diff --git a/include/sysemu/os-posix.h b/include/sysemu/os-posix.h 
>> index 7f198e4..2f2ead6 100644
>> --- a/include/sysemu/os-posix.h
>> +++ b/include/sysemu/os-posix.h
>> @@ -31,6 +31,7 @@ void os_set_proc_name(const char *s);  void 
>> os_setup_signal_handling(void);  void os_daemonize(void);  void 
>> os_setup_post(void);
>> +void os_mlock(void);
>>  
>>  typedef struct timeval qemu_timeval;  #define qemu_gettimeofday(tp) 
>> gettimeofday(tp, NULL) diff --git a/include/sysemu/os-win32.h 
>> b/include/sysemu/os-win32.h index bf9edeb..a74ca13 100644
>> --- a/include/sysemu/os-win32.h
>> +++ b/include/sysemu/os-win32.h
>> @@ -80,6 +80,7 @@ static inline void os_daemonize(void) {}  static 
>> inline void os_setup_post(void) {}  void os_set_line_buffering(void);  
>> static inline void os_set_proc_name(const char *dummy) {}
>> +static inline void os_mlock(void) {}
>>  
>>  #if !defined(EPROTONOSUPPORT)
>>  # define EPROTONOSUPPORT EINVAL
>> diff --git a/os-posix.c b/os-posix.c
>> index 5c64518..1304b0e 100644
>> --- a/os-posix.c
>> +++ b/os-posix.c
>> @@ -363,3 +363,11 @@ bool is_daemonized(void)  {
>>      return daemonize;
>>  }
>> +
>> +void os_mlock(void)
>> +{
>> +    if (mlockall(MCL_CURRENT | MCL_FUTURE)) {
>> +        perror("mlockall");
>> +        exit(1);
>> +    }
>> +}
>> diff --git a/qemu-options.hx b/qemu-options.hx index 9d7131a..843fcb4 
>> 100644
>> --- a/qemu-options.hx
>> +++ b/qemu-options.hx
>> @@ -2464,6 +2464,19 @@ STEXI
>>  Do not start CPU at startup (you must type 'c' in the monitor).
>>  ETEXI
>>  
>> +DEF("realtime", HAS_ARG, QEMU_OPTION_realtime,
>> +    "-realtime [mlock=on|off]\n"
>> +    "                run qemu with realtime features\n"
>> +    "                mlock=on|off controls mlock support (default: on)\n",
>> +    QEMU_ARCH_ALL)
>> +STEXI
>> address@hidden -realtime mlock=on|off
>> address@hidden -realtime
>> +Run qemu with realtime features.
>> +mlocking qemu and guest memory can be enabled via @option{mlock=on} 
>> +(enabled by default).
>> +ETEXI
>> +
>>  DEF("gdb", HAS_ARG, QEMU_OPTION_gdb, \
>>      "-gdb dev        wait for gdb connection on 'dev'\n", QEMU_ARCH_ALL)
>>  STEXI
>> diff --git a/vl.c b/vl.c
>> index 1355f69..c16c8ad 100644
>> --- a/vl.c
>> +++ b/vl.c
>> @@ -491,6 +491,18 @@ static QemuOptsList qemu_object_opts = {
>>      },
>>  };
>>  
>> +static QemuOptsList qemu_realtime_opts = {
>> +    .name = "realtime",
>> +    .head = QTAILQ_HEAD_INITIALIZER(qemu_realtime_opts.head),
>> +    .desc = {
>> +        {
>> +            .name = "mlock",
>> +            .type = QEMU_OPT_BOOL,
>> +        },
>> +        { /* end of list */ }
>> +    },
>> +};
>> +
>>  const char *qemu_get_vm_name(void)
>>  {
>>      return qemu_name;
>> @@ -1384,6 +1396,17 @@ static void smp_parse(const char *optarg)
>>          max_cpus = smp_cpus;
>>  }
>>  
>> +static void configure_realtime(QemuOpts *opts) {
>> +    bool is_mlock;
>> +
>> +    is_mlock = qemu_opt_get_bool(opts, "mlock", true);
>> +
>> +    if (is_mlock) {
>> +        os_mlock();
>> +    }
>> +}
>> +
>>  /***********************************************************/
>>  /* USB devices */
>>  
>> @@ -2860,6 +2883,7 @@ int main(int argc, char **argv, char **envp)
>>      qemu_add_opts(&qemu_sandbox_opts);
>>      qemu_add_opts(&qemu_add_fd_opts);
>>      qemu_add_opts(&qemu_object_opts);
>> +    qemu_add_opts(&qemu_realtime_opts);
>>  
>>      runstate_init();
>>  
>> @@ -3806,6 +3830,13 @@ int main(int argc, char **argv, char **envp)
>>                      exit(1);
>>                  }
>>                  break;
>> +            case QEMU_OPTION_realtime:
>> +                opts = qemu_opts_parse(qemu_find_opts("realtime"), optarg, 
>> 0);
>> +                if (!opts) {
>> +                    exit(1);
>> +                }
>> +                configure_realtime(opts);
>> +                break;
>>              default:
>>                  os_parse_cmd_args(popt->index, optarg);
>>              }
>>
> 
>