Date: Mon, 12 Jan 2015 00:27:18 -0500 From: Allan Jude <allanjude@freebsd.org> To: freebsd-hackers@freebsd.org Subject: Re: [PATCH] Display progress during getmemsize() so the kernel doesn't look like it hanged Message-ID: <54B35B36.4040504@freebsd.org> In-Reply-To: <D0D89A8E.129518%rpokala@panasas.com> References: <D0D89A8E.129518%rpokala@panasas.com>
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On 2015-01-12 00:24, Pokala, Ravi wrote:
> Hi folks,
>
> Several of us have noticed that there's a long pause at the start of
> booting the kernel on amd64 systems with large amounts of RAM. During this
> pause, the kernel is mapping in the memory ranges, but does not emit any
> progress indicators. Because this can take quite a while, it can look like
> the kernel has hung. I filed PR 196650 about this issue; this patch just
> prints out a dot for every GB that's mapped in. We've been using this
> patch for years at Panasas, and I'm hoping someone can submit it for me.
>
> Thanks,
>
> Ravi
>
>
> Index: sys/amd64/amd64/machdep.c
> ===================================================================
> --- sys/amd64/amd64/machdep.c (revision 276903)
> +++ sys/amd64/amd64/machdep.c (working copy)
> @@ -1575,6 +1575,9 @@
> u_long physmem_start, physmem_tunable, memtest;
> pt_entry_t *pte;
> quad_t dcons_addr, dcons_size;
> + u_int32_t page_counter;
> + int PAGES_PER_MB = ((1024 * 1024) / PAGE_SIZE);
> + int PAGES_PER_GB = (PAGES_PER_MB * 1024);
>
> bzero(physmap, sizeof(physmap));
> basemem = 0;
> @@ -1678,6 +1681,8 @@
> * physmap is in bytes, so when converting to page boundaries,
> * round up the start address and round down the end address.
> */
> + printf("Mapping system memory");
> + page_counter = 0;
> for (i = 0; i <= physmap_idx; i += 2) {
> vm_paddr_t end;
>
> @@ -1688,6 +1693,14 @@
> int tmp, page_bad, full;
> int *ptr = (int *)CADDR1;
>
> + /*
> + * Print a "." every GB, to show we're making progress
> + */
> + page_counter++;
> + if ((page_counter % PAGES_PER_GB) == 0) {
> + printf(".");
> + }
> +
> full = FALSE;
> /*
> * block out kernel memory as not available.
> @@ -1792,6 +1805,9 @@
> break;
> }
> }
> + printf("\nMapped %d GB + %d MB total\n",
> + (page_counter / PAGES_PER_GB),
> + ((page_counter % PAGES_PER_GB) / PAGES_PER_MB));
> *pte = 0;
> invltlb();
>
>
>
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>
Which version(s) of FreeBSD were you seeing this delay on?
I know older versions had it, quite badly.
setting hw.memtest.tests=0 in /boot/loader.conf makes most of the delay
go away, and the default on -CURRENT is now 0 instead of 1.
IIRC, in 10, it defaults to 1, but is switched to 0 in the case of
virtual machines, because touching every page of memory ruined memory
over-commit type features.
Is this feature still useful with memtest.tests=0?
--
Allan Jude
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