Date: Mon, 4 Jun 2012 17:23:49 -0400 From: John Baldwin <jhb@freebsd.org> To: Giovanni Trematerra <gianni@freebsd.org> Cc: Alan Cox <alc@rice.edu>, Alexander Kabaev <kan@freebsd.org>, Attilio Rao <attilio@freebsd.org>, freebsd-arch@freebsd.org, Konstantin Belousov <kostikbel@gmail.com> Subject: Re: Fwd: [RFC] Kernel shared variables Message-ID: <201206041723.49562.jhb@freebsd.org> In-Reply-To: <CACfq0933BwaverZinGvKtErPvdZp%2B4jQRUFQukK9V_QemRsW9g@mail.gmail.com> References: <CACfq090r1tWhuDkxdSZ24fwafbVKU0yduu1yV2%2BoYo%2BwwT4ipA@mail.gmail.com> <20120604181917.GD85127@deviant.kiev.zoral.com.ua> <CACfq0933BwaverZinGvKtErPvdZp%2B4jQRUFQukK9V_QemRsW9g@mail.gmail.com>
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On Monday, June 04, 2012 5:16:10 pm Giovanni Trematerra wrote: > On Mon, Jun 4, 2012 at 8:19 PM, Konstantin Belousov <kostikbel@gmail.com> wrote: > > On Mon, Jun 04, 2012 at 11:01:57AM -0400, John Baldwin wrote: > >> On Sunday, June 03, 2012 6:49:27 am Bruce Evans wrote: > >> > On Sun, 3 Jun 2012, Konstantin Belousov wrote: > > >> I think duplicating this logic in userland would just be wasteful. I have > >> a private fast gettimeofday() at my current job and it works by exporting > >> the current timehands structure (well, the equivalent) to userland. The > >> userland bits then fetch a copy of the details and do the same as bintime(). > >> (I move the math (bintime_addx() and the multiply)) out of the loop however. > > I started yesterday an implementation which uses shared page to export > > some variant of timehands, and uses auxv to provide the libc with a pointer > > to timehands when rdtsc is reasonable. > > > > I almost finished both 32bit and 64bit userspace, but there is > > kernel-side work left. Is your implementation ready or close to be ready > > for commit ? In other words, should I drop the efforts, or continue ? > > > > Hey wait, What are you doing? > This is completely unfair. You didn't even review my patch. > I really don't understand your way to completely ignore me and start implement > yesterday something you didn't care about for more than 3 years. > It costs me a lot of time and energy and I think I deserve more respect that > just be ignored. In fairness, I would not be able to use your version of gettimeofday(). My application requires something where we can interpolate based on the value of rdtsc(). Also, I don't really see the need to export anything other than the details to make gettimeofday() faster. I don't see a practical need for using shared variables for getpid(), getpgid(), getppid(), getuid(), or the like. -- John Baldwin
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