Date: Fri, 21 Oct 2005 15:04:30 -0700 From: Julian Elischer <julian@elischer.org> To: John Baldwin <jhb@freebsd.org> Cc: nocool <nocool@263.net>, freebsd-hackers@freebsd.org, David Schultz <das@freebsd.org>, freebsd-current <freebsd-current@freebsd.org>, delphij <delphij@freebsd.org> Subject: Re: where to release proc.p_stats Message-ID: <435965EE.7070504@elischer.org> In-Reply-To: <200510211728.32476.jhb@freebsd.org> References: <20051021131329.A16FC126E@smtp.263.net> <200510211239.35190.jhb@freebsd.org> <20051021203207.GA26616@VARK.MIT.EDU> <200510211728.32476.jhb@freebsd.org>
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John Baldwin wrote:
>On Friday 21 October 2005 04:32 pm, David Schultz wrote:
>
>
>>On Fri, Oct 21, 2005, John Baldwin wrote:
>>
>>
>>>On Friday 21 October 2005 09:13 am, nocool wrote:
>>>
>>>
>>>>freebsd-hackersļ¼hello
>>>>
>>>> Question about 5.4 kernel source code.
>>>> I have some question about strust proc's initialize. Kernel use
>>>>proc_zone to allocate proc items and initialize them with proc_init
>>>>(sys\kern\kern_proc.c) function. In this function, we can find the
>>>>field proc.p_stats is allocated with pstats_alloc(), as
>>>>
>>>>p->p_stats = pstats_alloc();
>>>>
>>>>and pstats_alloc is realized as
>>>>
>>>>malloc(sizeof(struct pstats), M_SUBPROC, M_ZERO|M_WAITOK);
>>>>
>>>>But I can't find where this field is freed. If it will not be release,
>>>>will there be memory leakage?
>>>>
>>>>
>>>Heh, das@ forgot to call pstats_free() when he did the changes. The
>>>reason is probably because proc_fini() doesn't do anything useful because
>>>we never recycle proc structs. We should probably at least add the
>>>operations there though for documentation purposes. Something like this
>>>would work I think:
>>>
>>>
>>I didn't put in the call because we never free proc structures, but
>>documenting what should happen if we ever do free them is a good
>>idea. There's a fair amount of other cleanup that needs to happen
>>as well, which you can probably find in the CVS history. (IIRC,
>>I'm guilty of removing the code at a time when more things depended
>>upon struct proc being type safe. Are there any remaining reasons
>>why we can't free struct procs at this point?)
>>
>>By the way, there's no reason why we can't fold struct pstats into
>>struct proc so we don't have to allocate and free it at all.
>>It's never shared, so the extra level of indirection just adds overhead.
>>The main reason I didn't make this change earlier was to maintain binary
>>compatibility when I backported my U-area changes to -STABLE.
>>
>>
>
>Looks like some of the functions (vm_dispose_proc() and sched_destroyproc())
>have vanished, so this is all that would be in there now:
>
>Index: kern_proc.c
>===================================================================
>RCS file: /usr/cvs/src/sys/kern/kern_proc.c,v
>retrieving revision 1.232
>diff -u -r1.232 kern_proc.c
>--- kern_proc.c 2 Oct 2005 23:27:56 -0000 1.232
>+++ kern_proc.c 21 Oct 2005 21:21:45 -0000
>@@ -196,8 +196,17 @@
> static void
> proc_fini(void *mem, int size)
> {
>+#ifdef notnow
>+ struct proc *p;
>
>+ p = (struct proc *)mem;
>+ pstats_free(p->p_stats);
>+ ksegrp_free(FIRST_KSEGRP_IN_PROC(p));
>+ thread_free(FIRST_THREAD_IN_PROC(p));
>+ mtx_destroy(&p->p_mtx);
>+#else
> panic("proc reclaimed");
>+#endif
> }
>
> /*
>
>
>
sched_destroyproc was removed by someone I believe because "it was not
used".
if you were removing a proc you possibly should re introduce it.
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