From: Michael Kerrisk <mtk.manpages@gmail.com>
To: "Carlos O'Donell" <carlos@redhat.com>
Cc: Siddhesh Poyarekar <siddhesh@sourceware.org>,
libc-alpha <libc-alpha@sourceware.org>,
Michael Kerrisk-manpages <mtk.manpages@gmail.com>
Subject: Re: [PATCH 1/2] Add note on MALLOC_MMAP_* environment variables
Date: Wed, 26 Oct 2016 07:58:00 -0000 [thread overview]
Message-ID: <CALxWeYq+KofiO6AGqggzNFNmV=dVXfwyMsQcXL+=z5A6P3XcYA@mail.gmail.com> (raw)
In-Reply-To: <57acdb4a-ef0b-0bd8-bc8d-6bb8bbc3aaab@redhat.com>
I've nothing to add beyond Carlos's comments. I looked this over and
it looks good to me.
Cheers,
Michael
On Wed, Oct 26, 2016 at 6:15 AM, Carlos O'Donell <carlos@redhat.com> wrote:
> On 10/24/2016 10:07 AM, Siddhesh Poyarekar wrote:
>> The mallopt parameters manual does not mention the environment
>> variables that can be used to set these parameters at program startup.
>> Mention those environment variables for completeness.
>>
>> * manual/memory.texi: Add environment variable alternatives to
>> setting mallopt parameters.
>
> Two nits. Otherwise OK.
>
>> ---
>> manual/memory.texi | 31 +++++++++++++++++++++++++++++++
>> 1 file changed, 31 insertions(+)
>>
>> diff --git a/manual/memory.texi b/manual/memory.texi
>> index 5383105..6f33455 100644
>> --- a/manual/memory.texi
>> +++ b/manual/memory.texi
>> @@ -1113,12 +1113,25 @@ choices for @var{param}, as defined in @file{malloc.h}, are:
>> @item M_MMAP_MAX
>> The maximum number of chunks to allocate with @code{mmap}. Setting this
>> to zero disables all use of @code{mmap}.
>> +
>> +The default value of this parameter is @code{65536}.
>> +
>> +This parameter can also be set for the process at startup by setting the
>> +environment variable @code{MALLOC_MMAP_MAX_} to the desired value.
>> @item M_MMAP_THRESHOLD
>> All chunks larger than this value are allocated outside the normal
>> heap, using the @code{mmap} system call. This way it is guaranteed
>> that the memory for these chunks can be returned to the system on
>> @code{free}. Note that requests smaller than this threshold might still
>> be allocated via @code{mmap}.
>> +
>> +If this parameter is not set, the default value is set as 128 KB and the
>
> Should this be 128KiB?
>
>> +threshold is adjusted dynamically to suit the allocation patterns of the
>> +program. If the parameter is set, the dynamic adjustment is disabled and the
>> +value is set statically to the input value.
>> +
>> +This parameter can also be set for the process at startup by setting the
>> +environment variable @code{MALLOC_MMAP_THRESHOLD_} to the desired value.
>> @comment TODO: @item M_MXFAST
>> @item M_PERTURB
>> If non-zero, memory blocks are filled with values depending on some
>> @@ -1128,16 +1141,34 @@ use of uninitialized or freed heap memory. Note that this option does not
>> guarantee that the freed block will have any specific values. It only
>> guarantees that the content the block had before it was freed will be
>> overwritten.
>> +
>> +The default value of this parameter is @code{0}.
>> +
>> +This parameter can also be set for the process at startup by setting the
>> +environment variable @code{MALLOC_MMAP_PERTURB_} to the desired value.
>> @item M_TOP_PAD
>> This parameter determines the amount of extra memory to obtain from the
>> system when a call to @code{sbrk} is required. It also specifies the
>> number of bytes to retain when shrinking the heap by calling @code{sbrk}
>> with a negative argument. This provides the necessary hysteresis in
>> heap size such that excessive amounts of system calls can be avoided.
>> +
>> +The default value of this parameter is @code{0}.
>> +
>> +This parameter can also be set for the process at startup by setting the
>> +environment variable @code{MALLOC_TOP_PAD_} to the desired value.
>> @item M_TRIM_THRESHOLD
>> This is the minimum size (in bytes) of the top-most, releasable chunk
>> that will cause @code{sbrk} to be called with a negative argument in
>> order to return memory to the system.
>> +
>> +If this parameter is not set, the default value is set as 128 KB and the
>
> Likewise.
>
>> +threshold is adjusted dynamically to suit the allocation patterns of the
>> +program. If the parameter is set, the dynamic adjustment is disabled and the
>> +value is set statically to the provided input.
>> +
>> +This parameter can also be set for the process at startup by setting the
>> +environment variable @code{MALLOC_TRIM_THRESHOLD_} to the desired value.
>> @end table
>>
>> @end deftypefun
>>
>
>
> --
> Cheers,
> Carlos.
next prev parent reply other threads:[~2016-10-26 7:58 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-24 14:08 [PATCH 0/2] Malloc manual cleanups Siddhesh Poyarekar
2016-10-24 14:08 ` [PATCH 1/2] Add note on MALLOC_MMAP_* environment variables Siddhesh Poyarekar
2016-10-26 4:18 ` Carlos O'Donell
2016-10-26 7:58 ` Michael Kerrisk [this message]
2016-10-26 9:47 ` Siddhesh Poyarekar
2016-10-26 11:26 ` Rical Jasan
2016-10-26 11:30 ` Siddhesh Poyarekar
2016-10-26 12:04 ` Rical Jasan
2016-10-24 14:08 ` [PATCH 2/2] Document the M_ARENA_* mallopt parameters Siddhesh Poyarekar
2016-10-25 7:51 ` Rical Jasan
2016-10-25 21:55 ` DJ Delorie
2016-10-26 5:42 ` Siddhesh Poyarekar
-- strict thread matches above, loose matches on Subject: below --
2016-10-10 17:26 [PATCH 1/2] Add note on MALLOC_MMAP_* environment variables Siddhesh Poyarekar
2016-10-10 17:33 ` DJ Delorie
2016-10-10 17:42 ` Siddhesh Poyarekar
2016-10-11 6:20 ` Michael Kerrisk
2016-10-11 18:19 ` DJ Delorie
2016-10-11 19:03 ` Michael Kerrisk (man-pages)
2016-10-12 11:57 ` Siddhesh Poyarekar
2016-10-17 19:40 ` Carlos O'Donell
2016-10-11 19:35 ` Kalle Olavi Niemitalo
2016-10-17 16:13 ` Carlos O'Donell
2016-10-17 16:16 ` Siddhesh Poyarekar
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