Date: Wed, 4 Sep 2013 09:20:42 -0400 From: Ryan Stone <rysto32@gmail.com> To: Nathan Whitehorn <nwhitehorn@freebsd.org> Cc: freebsd-geom@freebsd.org, "freebsd-hackers@freebsd.org" <freebsd-hackers@freebsd.org>, Alexander Motin <mav@freebsd.org>, "freebsd-current@freebsd.org" <freebsd-current@freebsd.org>, Outback Dingo <outbackdingo@gmail.com>, =?ISO-8859-1?Q?Olivier_Cochard=2DLabb=E9?= <olivier@cochard.me>, FreeBSD SCSI <freebsd-scsi@freebsd.org> Subject: Re: [RFC][CFT] GEOM direct dispatch and fine-grained CAM locking Message-ID: <CAFMmRNzkL%2BuOsC=2Cq_S4Zm5fkmrQRNYcKfijA8yyYcxvLaXPQ@mail.gmail.com> In-Reply-To: <52272B6F.9060308@freebsd.org> References: <520D4ADB.50209@FreeBSD.org> <5224511D.4090503@FreeBSD.org> <20130903134251.GB43281@caravan.chchile.org> <CAKYr3zwjQ9K1c5smZXTESa3T5UnchYaipYQCS2OAJOUFyPBGww@mail.gmail.com> <CA%2Bq%2BTcoeHDbkCOXvBjbbzOKCbb7RLYqG0jn9bHNn_CZgLGarLg@mail.gmail.com> <5226DAB0.1060303@FreeBSD.org> <52272B6F.9060308@freebsd.org>
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On Wed, Sep 4, 2013 at 8:45 AM, Nathan Whitehorn <nwhitehorn@freebsd.org> wrote: > Could you describe what this macro is supposed to do so that we can do the > porting work? > -Nathan #define GET_STACK_USAGE(total, used) GET_STACK_USAGE sets the variable passed in total to the total amount of stack space available to the current thread. used is set to the amount of stack space currently used (this does not have to have byte-precision). Netgraph uses this to decide when to stop recursing and instead defer to a work queue (to prevent stack overflow). I presume that Alexander is using it in a similar way. It looks like the amd64 version could be ported to other architectures quite easily if you were to account for stacks that grow up and stacks that grow down: http://svnweb.freebsd.org/base/head/sys/amd64/include/proc.h?revision=233291&view=markup /* Get the current kernel thread stack usage. */ #define GET_STACK_USAGE(total, used) do { \ struct thread *td = curthread; \ (total) = td->td_kstack_pages * PAGE_SIZE; \ (used) = (char *)td->td_kstack + \ td->td_kstack_pages * PAGE_SIZE - \ (char *)&td; \ } while (0)
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