From: Arnd Bergmann <arnd@arndb•de>
To: linuxppc-dev@ozlabs•org
Cc: Kumar Gala <kumar.gala@freescale•com>
Subject: Re: [PATCH 6/16] powerpc/mm: Split mmu_context handling v3
Date: Mon, 15 Dec 2008 16:43:44 +0100 [thread overview]
Message-ID: <200812151643.44944.arnd@arndb.de> (raw)
In-Reply-To: <20081215054530.4835FDE00C@ozlabs.org>
On Monday 15 December 2008, Benjamin Herrenschmidt wrote:
> +/*
> + * On 32-bit PowerPC 6xx/7xx/7xxx CPUs, we use a set of 16 VSIDs
> + * (virtual segment identifiers) for each context. Although the
> + * hardware supports 24-bit VSIDs, and thus >1 million contexts,
> + * we only use 32,768 of them. That is ample, since there can be
> + * at most around 30,000 tasks in the system anyway, and it means
> + * that we can use a bitmap to indicate which contexts are in use.
> + * Using a bitmap means that we entirely avoid all of the problems
> + * that we used to have when the context number overflowed,
> + * particularly on SMP systems.
> + * -- paulus.
> + */
Didn't we lift the limit to 30,000 tasks at some point? The comment
in linux/threads.h mentions that the PID space goes up to 4 million.
What does actually happen when we increase pid_max to beyond 32768
on those systems and try to use them? Is there another limit in place?
Arnd <><
next prev parent reply other threads:[~2008-12-15 15:43 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-12-15 5:43 [PATCH 0/16] powerpc: Preliminary work to enable SMP BookE (v2) Benjamin Herrenschmidt
2008-12-15 5:44 ` [PATCH 1/16] powerpc: Fix bogus cache flushing on all 40x and BookE processors v2 Benjamin Herrenschmidt
2008-12-15 5:44 ` [PATCH 2/16] powerpc: Fix asm EMIT_BUG_ENTRY with !CONFIG_BUG Benjamin Herrenschmidt
2008-12-15 5:44 ` [PATCH 3/16] powerpc/4xx: Extended DCR support v2 Benjamin Herrenschmidt
2008-12-17 17:33 ` Josh Boyer
2008-12-15 5:44 ` [PATCH 4/16] powerpc/fsl-booke: Fix problem with _tlbil_va Benjamin Herrenschmidt
2008-12-15 6:59 ` Stephen Rothwell
2008-12-15 7:04 ` Benjamin Herrenschmidt
2008-12-15 5:44 ` [PATCH 5/16] powerpc/mm: Add local_flush_tlb_mm() to SW loaded TLB implementations Benjamin Herrenschmidt
2008-12-15 20:30 ` Kumar Gala
2008-12-15 5:44 ` [PATCH 6/16] powerpc/mm: Split mmu_context handling v3 Benjamin Herrenschmidt
2008-12-15 15:43 ` Arnd Bergmann [this message]
2008-12-15 20:20 ` Benjamin Herrenschmidt
2008-12-15 5:44 ` [PATCH 7/16] powerpc/mm: Rework context management for CPUs with no hash table v2 Benjamin Herrenschmidt
2008-12-17 21:30 ` Kumar Gala
2008-12-15 5:44 ` [PATCH 8/16] powerpc/mm: Rename tlb_32.c and tlb_64.c to tlb_hash32.c and tlb_hash64.c Benjamin Herrenschmidt
2008-12-15 20:36 ` Kumar Gala
2008-12-15 20:46 ` Benjamin Herrenschmidt
2008-12-15 5:44 ` [PATCH 9/16] powerpc/mm: Introduce MMU features v2 Benjamin Herrenschmidt
2008-12-15 5:44 ` [PATCH 10/16] powerpc/mm: Remove flush_HPTE() Benjamin Herrenschmidt
2008-12-15 5:44 ` [PATCH 11/16] powerpc/mm: Add SMP support to no-hash TLB handling v3 Benjamin Herrenschmidt
2008-12-15 20:19 ` Kumar Gala
2008-12-15 20:46 ` Benjamin Herrenschmidt
2008-12-15 20:57 ` Kumar Gala
2008-12-15 21:03 ` Benjamin Herrenschmidt
2008-12-15 21:10 ` Kumar Gala
2008-12-15 21:18 ` Benjamin Herrenschmidt
2008-12-15 22:19 ` Kumar Gala
2008-12-15 23:31 ` Benjamin Herrenschmidt
2008-12-15 5:45 ` [PATCH 12/16] powerpc/mm: Split low level tlb invalidate for nohash processors Benjamin Herrenschmidt
2008-12-15 5:45 ` [PATCH 13/16] powerpc/44x: No need to mask MSR:CE, ME or DE in _tlbil_va on 440 Benjamin Herrenschmidt
2008-12-15 12:25 ` [PATCH 13/16] powerpc/44x: No need to mask MSR:CE,ME " Josh Boyer
2008-12-15 5:45 ` [PATCH 14/16] powerpc/mm: Runtime allocation of mmu context maps for nohash CPUs v2 Benjamin Herrenschmidt
2008-12-17 21:21 ` Kumar Gala
2008-12-15 5:45 ` [PATCH 15/16] powerpc/mm: Rework usage of _PAGE_COHERENT/NO_CACHE/GUARDED Benjamin Herrenschmidt
2008-12-15 20:54 ` Kumar Gala
2008-12-15 21:01 ` Benjamin Herrenschmidt
2008-12-15 21:08 ` Kumar Gala
2008-12-15 21:03 ` Michael Ellerman
2008-12-15 21:05 ` Benjamin Herrenschmidt
2008-12-15 5:45 ` [PATCH 16/16] powerpc/44x: 44x TLB doesn't need "Guarded" set for all pages Benjamin Herrenschmidt
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=200812151643.44944.arnd@arndb.de \
--to=arnd@arndb$(echo .)de \
--cc=kumar.gala@freescale$(echo .)com \
--cc=linuxppc-dev@ozlabs$(echo .)org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox