When a malformed loglevel value (for example "${abc}") is passed on the
kernel cmdline, the loglevel itself is being set to 0.
That then suppresses all following messages, including all the errors
and crashes caused by other malformed cmdline options. This could make
debugging process quite tricky.
This patch leaves the previous value of loglevel if the new value is
incorrect and reports an error code in this case.
Signed-off-by: Alexander Sverdlin <alexander.sverdlin@sysgo.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The core device layer sends tons of uevent notifications for each device
it finds, and if the kernel has been built with a non-empty
CONFIG_UEVENT_HELPER_PATH that will make us try to execute the usermode
helper binary for all these events very early in the boot.
Not only won't the root filesystem even be mounted at that point, we
literally won't have necessarily even initialized all the process
handling data structures at that point, which causes no end of silly
problems even when the usermode helper doesn't actually succeed in
executing.
So just use our existing infrastructure to disable the usermodehelpers
to make the kernel start out with them disabled. We enable them when
we've at least initialized stuff a bit.
Problems related to an uninitialized
init_ipc_ns.ids[IPC_SHM_IDS].rw_mutex
reported by various people.
Reported-by: Manuel Lauss <manuel.lauss@googlemail.com>
Reported-by: Richard Weinberger <richard@nod.at>
Reported-by: Marc Zyngier <maz@misterjones.org>
Acked-by: Kay Sievers <kay.sievers@vrfy.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Vasiliy Kulikov <segoon@openwall.com>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
While it's at its least, make a number of boring nitpicky cleanups to
shmem.c, mostly for consistency of variable naming. Things like "swap"
instead of "entry", "pgoff_t index" instead of "unsigned long idx".
And since everything else here is prefixed "shmem_", better change
init_tmpfs() to shmem_init().
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
For each CPU, do the calibration delay only once. For subsequent calls,
use the cached per-CPU value of loops_per_jiffy.
This saves about 200ms of resume time on dual core Intel Atom N5xx based
systems. This helps bring down the kernel resume time on such systems
from about 500ms to about 300ms.
[akpm@linux-foundation.org: make cpu_loops_per_jiffy static]
[akpm@linux-foundation.org: clean up message text]
[akpm@linux-foundation.org: fix things up after upstream rmk changes]
Signed-off-by: Sameer Nanda <snanda@chromium.org>
Cc: Phil Carmody <ext-phil.2.carmody@nokia.com>
Cc: Andrew Worsley <amworsley@gmail.com>
Cc: David Daney <ddaney@caviumnetworks.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
um: Make rwsem.S depend on CONFIG_RWSEM_XCHGADD_ALGORITHM
* 'core-debug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
debug: Make CONFIG_EXPERT select CONFIG_DEBUG_KERNEL to unhide debug options
* 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
genirq: Remove unused CHECK_IRQ_PER_CPU()
* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
perf tools, x86: Fix 32-bit compile on 64-bit system
* 'timers-cleanup-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
mips: Fix i8253 clockevent fallout
i8253: Cleanup outb/inb magic
arm: Footbridge: Use common i8253 clockevent
mips: Use common i8253 clockevent
x86: Use common i8253 clockevent
i8253: Create common clockevent implementation
i8253: Export i8253_lock unconditionally
pcpskr: MIPS: Make config dependencies finer grained
pcspkr: Cleanup Kconfig dependencies
i8253: Move remaining content and delete asm/i8253.h
i8253: Consolidate definitions of PIT_LATCH
x86: i8253: Consolidate definitions of global_clock_event
i8253: Alpha, PowerPC: Remove unused asm/8253pit.h
alpha: i8253: Cleanup remaining users of i8253pit.h
i8253: Remove I8253_LOCK config
i8253: Make pcsp sound driver use the shared i8253_lock
i8253: Make pcspkr input driver use the shared i8253_lock
i8253: Consolidate all kernel definitions of i8253_lock
i8253: Unify all kernel declarations of i8253_lock
i8253: Create linux/i8253.h and use it in all 8253 related files
Secondary CPU bringup typically calls calibrate_delay() during its
initialization. However, calibrate_delay() modifies a global variable
(loops_per_jiffy) used for udelay() and __delay().
A side effect of 71c696b1 ("calibrate: extract fall-back calculation
into own helper") introduced in the 2.6.39 merge window means that we
end up with a substantial period where loops_per_jiffy is zero. This
causes the spinlock debugging code to malfunction:
u64 loops = loops_per_jiffy * HZ;
for (;;) {
for (i = 0; i < loops; i++) {
if (arch_spin_trylock(&lock->raw_lock))
return;
__delay(1);
}
...
}
by never calling arch_spin_trylock() - resulting in the CPU locking
up in an infinite loop inside __spin_lock_debug().
Work around this by only writing to loops_per_jiffy only once we have
completed all the calibration decisions.
Tested-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Cc: <stable@kernel.org> (2.6.39-stable)
--
Better solutions (such as omitting the calibration for secondary CPUs,
or arranging for calibrate_delay() to return the LPJ value and leave
it to the caller to decide where to store it) are a possibility, but
would be much more invasive into each architecture.
I think this is the best solution for -rc and stable, but it should be
revisited for the next merge window.
init/calibrate.c | 14 ++++++++------
1 files changed, 8 insertions(+), 6 deletions(-)
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There is a problem that kdump(2nd kernel) sometimes hangs up due
to a pending IPI from 1st kernel. Kernel panic occurs because IPI
comes before call_single_queue is initialized.
To fix the crash, rename init_call_single_data() to call_function_init()
and call it in start_kernel() so that call_single_queue can be
initialized before enabling interrupts.
The details of the crash are:
(1) 2nd kernel boots up
(2) A pending IPI from 1st kernel comes when irqs are first enabled
in start_kernel().
(3) Kernel tries to handle the interrupt, but call_single_queue
is not initialized yet at this point. As a result, in the
generic_smp_call_function_single_interrupt(), NULL pointer
dereference occurs when list_replace_init() tries to access
&q->list.next.
Therefore this patch changes the name of init_call_single_data()
to call_function_init() and calls it before local_irq_enable()
in start_kernel().
Signed-off-by: Takao Indoh <indou.takao@jp.fujitsu.com>
Reviewed-by: WANG Cong <xiyou.wangcong@gmail.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Milton Miller <miltonm@bga.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: kexec@lists.infradead.org
Link: http://lkml.kernel.org/r/D6CBEE2F420741indou.takao@jp.fujitsu.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
CONFIG_CONSTRUCTORS controls support for running constructor functions at
kernel init time. According to commit b99b87f70c ("kernel:
constructor support"), gcov (CONFIG_GCOV_KERNEL) needs this. However,
CONFIG_CONSTRUCTORS currently defaults to y, with no option to disable it,
and CONFIG_GCOV_KERNEL depends on it. Instead, default it to n and have
CONFIG_GCOV_KERNEL select it, so that the normal case of
CONFIG_GCOV_KERNEL=n will result in CONFIG_CONSTRUCTORS=n.
Observed in the short list of =y values in a minimal kernel configuration.
Signed-off-by: Josh Triplett <josh@joshtriplett.org>
Acked-by: WANG Cong <xiyou.wangcong@gmail.com>
Acked-by: Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Remove calibrate_delay_direct()'s KERN_DEBUG printk related to bogomips
calculation as it appears when booting every core on setups with
'ignore_loglevel' which dmesg people scan for possible issues. As the
message doesn't show very useful information to the widest audience of
kernel boot message gazers, it should be removed.
Introduced by commit d2b463135f ("init/calibrate.c: fix for critical
bogoMIPS intermittent calculation failure").
Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>
Cc: Andrew Worsley <amworsley@gmail.com>
Cc: Phil Carmody <ext-phil.2.carmody@nokia.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The "hostname" tool falls back to setting the hostname to "localhost" if
/etc/hostname does not exist. Distribution init scripts have the same
fallback. However, if userspace never calls sethostname, such as when
booting with init=/bin/sh, or otherwise booting a minimal system without
the usual init scripts, the default hostname of "(none)" remains,
unhelpfully appearing in various places such as prompts ("root@(none):~#")
and logs. Furthermore, "(none)" doesn't typically resolve to anything
useful.
Make the default hostname configurable. This removes the need for the
standard fallback, provides a useful default for systems that never call
sethostname, and makes minimal systems that much more useful with less
configuration. Distributions could choose to use "localhost" here to
avoid the fallback, while embedded systems may wish to use a specific
target hostname.
Signed-off-by: Josh Triplett <josh@joshtriplett.org>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: David Miller <davem@davemloft.net>
Cc: Serge Hallyn <serue@us.ibm.com>
Cc: Kel Modderman <kel@otaku42.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Several debugging options currently default to y, such as
CONFIG_DEBUG_BUGVERBOSE and CONFIG_DEBUG_RODATA. Embedded users
might want to turn those options off to save space; however,
turning them off requires turning on CONFIG_DEBUG_KERNEL to
unhide them. Since CONFIG_DEBUG_KERNEL exists specifically to
unhide debugging options, and CONFIG_EXPERT exists specifically
to unhide options potentially needed by experts and/or embedded
users, make CONFIG_EXPERT automatically imply
CONFIG_DEBUG_KERNEL.
Signed-off-by: Josh Triplett <josh@joshtriplett.org>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20110606012358.GA1909@leaf
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Thomas Gleixner reports that we now have a boot crash triggered by
CONFIG_CPUMASK_OFFSTACK=y:
BUG: unable to handle kernel NULL pointer dereference at (null)
IP: [<c11ae035>] find_next_bit+0x55/0xb0
Call Trace:
[<c11addda>] cpumask_any_but+0x2a/0x70
[<c102396b>] flush_tlb_mm+0x2b/0x80
[<c1022705>] pud_populate+0x35/0x50
[<c10227ba>] pgd_alloc+0x9a/0xf0
[<c103a3fc>] mm_init+0xec/0x120
[<c103a7a3>] mm_alloc+0x53/0xd0
which was introduced by commit de03c72cfc ("mm: convert
mm->cpu_vm_cpumask into cpumask_var_t"), and is due to wrong ordering of
mm_init() vs mm_init_cpumask
Thomas wrote a patch to just fix the ordering of initialization, but I
hate the new double allocation in the fork path, so I ended up instead
doing some more radical surgery to clean it all up.
Reported-by: Thomas Gleixner <tglx@linutronix.de>
Reported-by: Ingo Molnar <mingo@elte.hu>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The ns_cgroup is an annoying cgroup at the namespace / cgroup frontier and
leads to some problems:
* cgroup creation is out-of-control
* cgroup name can conflict when pids are looping
* it is not possible to have a single process handling a lot of
namespaces without falling in a exponential creation time
* we may want to create a namespace without creating a cgroup
The ns_cgroup was replaced by a compatibility flag 'clone_children',
where a newly created cgroup will copy the parent cgroup values.
The userspace has to manually create a cgroup and add a task to
the 'tasks' file.
This patch removes the ns_cgroup as suggested in the following thread:
https://lists.linux-foundation.org/pipermail/containers/2009-June/018616.html
The 'cgroup_clone' function is removed because it is no longer used.
This is a userspace-visible change. Commit 45531757b4 ("cgroup: notify
ns_cgroup deprecated") (merged into 2.6.27) caused the kernel to emit a
printk warning users that the feature is planned for removal. Since that
time we have heard from XXX users who were affected by this.
Signed-off-by: Daniel Lezcano <daniel.lezcano@free.fr>
Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Jamal Hadi Salim <hadi@cyberus.ca>
Reviewed-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Paul Menage <menage@google.com>
Acked-by: Matt Helsley <matthltc@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
On larger systems, because of the numerous ACPI, Bootmem and EFI messages,
the static log buffer overflows before the larger one specified by the
log_buf_len param is allocated. Minimize the overflow by allocating the
new log buffer as soon as possible.
On kernels without memblock, a later call to setup_log_buf from
kernel/init.c is the fallback.
[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: fix CONFIG_PRINTK=n build]
Signed-off-by: Mike Travis <travis@sgi.com>
Cc: Yinghai Lu <yhlu.kernel@gmail.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Jack Steiner <steiner@sgi.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
A fix to the TSC (Time Stamp Counter) based bogoMIPS calculation used on
secondary CPUs which has two faults:
1: Not handling wrapping of the lower 32 bits of the TSC counter on
32bit kernel - perhaps TSC is not reset by a warm reset?
2: TSC and Jiffies are no incrementing together properly. Either
jiffies increment too quickly or Time Stamp Counter isn't incremented
in during an SMI but the real time clock is and jiffies are
incremented.
Case 1 can result in a factor of 16 too large a value which makes udelay()
values too small and can cause mysterious driver errors. Case 2 appears
to give smaller 10-15% errors after averaging but enough to cause
occasional failures on my own board
I have tested this code on my own branch and attach patch suitable for
current kernel code. See below for examples of the failures and how the
fix handles these situations now.
I reported this issue earlier here:
Intermittent problem with BogoMIPs calculation on Intel AP CPUs -
http://marc.info/?l=linux-kernel&m=129947246316875&w=4
I suspect this issue has been seen by others but as it is intermittent and
bogoMIPS for secondary CPUs are no longer printed out it might have been
difficult to identify this as the cause. Perhaps these unresolved issues,
although quite old, might be relevant as possibly this fault has been
around for a while. In particular Case 1 may only be relevant to 32bit
kernels on newer HW (most people run 64bit kernels?). Case 2 is less
dramatic since the earlier fix in this area and also intermittent.
Re: bogomips discrepancy on Intel Core2 Quad CPU -
http://marc.info/?l=linux-kernel&m=118929277524298&w=4
slow system and bogus bogomips -
http://marc.info/?l=linux-kernel&m=116791286716107&w=4
Re: Re: [RFC-PATCH] clocksource: update lpj if clocksource has -
http://marc.info/?l=linux-kernel&m=128952775819467&w=4
This issue is masked a little by commit feae3203d7 ("timers, init:
Limit the number of per cpu calibration bootup messages") which only
prints out the first bogoMIPS value making it much harder to notice other
values differing. Perhaps it should be changed to only suppress them when
they are similar values?
Here are some outputs showing faults occurring and the new code handling
them properly. See my earlier message for examples of the original
failure.
Case 1: A Time Stamp Counter wrap:
...
Calibrating delay loop (skipped), value calculated using timer
frequency.. 6332.70 BogoMIPS (lpj=31663540)
....
calibrate_delay_direct() timer_rate_max=31666493
timer_rate_min=31666151 pre_start=4170369255 pre_end=4202035539
calibrate_delay_direct() timer_rate_max=2425955274
timer_rate_min=2425954941 pre_start=4265368533 pre_end=2396356387
calibrate_delay_direct() ignoring timer_rate as we had a TSC wrap
around start=4265368581 >=post_end=2396356511
calibrate_delay_direct() timer_rate_max=31666274
timer_rate_min=31665942 pre_start=2440373374 pre_end=2472039515
calibrate_delay_direct() timer_rate_max=31666492
timer_rate_min=31666160 pre_start=2535372139 pre_end=2567038422
calibrate_delay_direct() timer_rate_max=31666455
timer_rate_min=31666207 pre_start=2630371084 pre_end=2662037415
Calibrating delay using timer specific routine.. 6333.28 BogoMIPS (lpj=31666428)
Total of 2 processors activated (12665.99 BogoMIPS).
....
Case 2: Some thing (presumably the SMM interrupt?) causing the
very low increase in TSC counter for the DELAY_CALIBRATION_TICKS
increase in jiffies
...
Calibrating delay loop (skipped), value calculated using timer
frequency.. 6333.25 BogoMIPS (lpj=31666270)
...
calibrate_delay_direct() timer_rate_max=31666483
timer_rate_min=31666074 pre_start=4199536526 pre_end=4231202809
calibrate_delay_direct() timer_rate_max=864348 timer_rate_min=864016
pre_start=2405343672 pre_end=2406207897
calibrate_delay_direct() timer_rate_max=31666483
timer_rate_min=31666179 pre_start=2469540464 pre_end=2501206823
calibrate_delay_direct() timer_rate_max=31666511
timer_rate_min=31666122 pre_start=2564539400 pre_end=2596205712
calibrate_delay_direct() timer_rate_max=31666084
timer_rate_min=31665685 pre_start=2659538782 pre_end=2691204657
calibrate_delay_direct() dropping min bogoMips estimate 1 = 864348
Calibrating delay using timer specific routine.. 6333.27 BogoMIPS (lpj=31666390)
Total of 2 processors activated (12666.53 BogoMIPS).
...
After 70 boots I saw 2 variations <1% slip through
[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: fix straggly printk mess]
Signed-off-by: Andrew Worsley <amworsley@gmail.com>
Reviewed-by: Phil Carmody <ext-phil.2.carmody@nokia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
cpumask_t is very big struct and cpu_vm_mask is placed wrong position.
It might lead to reduce cache hit ratio.
This patch has two change.
1) Move the place of cpumask into last of mm_struct. Because usually cpumask
is accessed only front bits when the system has cpu-hotplug capability
2) Convert cpu_vm_mask into cpumask_var_t. It may help to reduce memory
footprint if cpumask_size() will use nr_cpumask_bits properly in future.
In addition, this patch change the name of cpu_vm_mask with cpu_vm_mask_var.
It may help to detect out of tree cpu_vm_mask users.
This patch has no functional change.
[akpm@linux-foundation.org: build fix]
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Koichi Yasutake <yasutake.koichi@jp.panasonic.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'kbuild' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild-2.6:
kbuild: make KBUILD_NOCMDDEP=1 handle empty built-in.o
scripts/kallsyms.c: fix potential segfault
scripts/gen_initramfs_list.sh: Convert to a /bin/sh script
kbuild: Fix GNU make v3.80 compatibility
kbuild: Fix passing -Wno-* options to gcc 4.4+
kbuild: move scripts/basic/docproc.c to scripts/docproc.c
kbuild: Fix Makefile.asm-generic for um
kbuild: Allow to combine multiple W= levels
kbuild: Disable -Wunused-but-set-variable for gcc 4.6.0
Fix handling of backlash character in LINUX_COMPILE_BY name
kbuild: asm-generic support
kbuild: implement several W= levels
kbuild: Fix build with binutils <= 2.19
initramfs: Use KBUILD_BUILD_TIMESTAMP for generated entries
kbuild: Allow to override LINUX_COMPILE_BY and LINUX_COMPILE_HOST macros
kbuild: Drop unused LINUX_COMPILE_TIME and LINUX_COMPILE_DOMAIN macros
kbuild: Use the deterministic mode of ar
kbuild: Call gzip with -n
kbuild: move KALLSYMS_EXTRA_PASS from Kconfig to Makefile
Kconfig: improve KALLSYMS_ALL documentation
Fix up trivial conflict in Makefile
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-next-2.6: (28 commits)
sparc32: fix build, fix missing cpu_relax declaration
SCHED_TTWU_QUEUE is not longer needed since sparc32 now implements IPI
sparc32,leon: Remove unnecessary page_address calls in LEON DMA API.
sparc: convert old cpumask API into new one
sparc32, sun4d: Implemented SMP IPIs support for SUN4D machines
sparc32, sun4m: Implemented SMP IPIs support for SUN4M machines
sparc32,leon: Implemented SMP IPIs for LEON CPU
sparc32: implement SMP IPIs using the generic functions
sparc32,leon: SMP power down implementation
sparc32,leon: added some SMP comments
sparc: add {read,write}*_be routines
sparc32,leon: don't rely on bootloader to mask IRQs
sparc32,leon: operate on boot-cpu IRQ controller registers
sparc32: always define boot_cpu_id
sparc32: removed unused code, implemented by generic code
sparc32: avoid build warning at mm/percpu.c:1647
sparc32: always register a PROM based early console
sparc32: probe for cpu info only during startup
sparc: consolidate show_cpuinfo in cpu.c
sparc32,leon: implement genirq CPU affinity
...
I still happen to believe that I$ miss costs are a major thing, but
sadly, -Os doesn't seem to be the solution. With or without it, gcc
will miss some obvious code size improvements, and with it enabled gcc
will sometimes make choices that aren't good even with high I$ miss
ratios.
For example, with -Os, gcc on x86 will turn a 20-byte constant memcpy
into a "rep movsl". While I sincerely hope that x86 CPU's will some day
do a good job at that, they certainly don't do it yet, and the cost is
higher than a L1 I$ miss would be.
Some day I hope we can re-enable this.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
