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kernel: add CLONE_IO to specifically request sharing of IO contexts

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syslets (or other threads/processes that want io context sharing) can
set this to enforce sharing of io context.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This commit is contained in:
Jens Axboe 2008-01-24 08:54:47 +01:00
parent 521f3bbdba
commit fadad878cc
2 changed files with 11 additions and 4 deletions
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1
include/linux/sched.h
View file

@ -27,6 +27,7 @@
#define CLONE_NEWUSER 0x10000000 /* New user namespace */ #define CLONE_NEWUSER 0x10000000 /* New user namespace */
#define CLONE_NEWPID 0x20000000 /* New pid namespace */ #define CLONE_NEWPID 0x20000000 /* New pid namespace */
#define CLONE_NEWNET 0x40000000 /* New network namespace */ #define CLONE_NEWNET 0x40000000 /* New network namespace */
#define CLONE_IO 0x80000000 /* Clone io context */
/* /*
* Scheduling policies * Scheduling policies

14
kernel/fork.c
View file

@ -792,15 +792,21 @@ out:
return error; return error;
} }
static int copy_io(struct task_struct *tsk) static int copy_io(unsigned long clone_flags, struct task_struct *tsk)
{ {
#ifdef CONFIG_BLOCK #ifdef CONFIG_BLOCK
struct io_context *ioc = current->io_context; struct io_context *ioc = current->io_context;
if (!ioc) if (!ioc)
return 0; return 0;
/*
if (ioprio_valid(ioc->ioprio)) { * Share io context with parent, if CLONE_IO is set
*/
if (clone_flags & CLONE_IO) {
tsk->io_context = ioc_task_link(ioc);
if (unlikely(!tsk->io_context))
return -ENOMEM;
} else if (ioprio_valid(ioc->ioprio)) {
tsk->io_context = alloc_io_context(GFP_KERNEL, -1); tsk->io_context = alloc_io_context(GFP_KERNEL, -1);
if (unlikely(!tsk->io_context)) if (unlikely(!tsk->io_context))
return -ENOMEM; return -ENOMEM;
@ -1176,7 +1182,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
goto bad_fork_cleanup_mm; goto bad_fork_cleanup_mm;
if ((retval = copy_namespaces(clone_flags, p))) if ((retval = copy_namespaces(clone_flags, p)))
goto bad_fork_cleanup_keys; goto bad_fork_cleanup_keys;
if ((retval = copy_io(p))) if ((retval = copy_io(clone_flags, p)))
goto bad_fork_cleanup_namespaces; goto bad_fork_cleanup_namespaces;
retval = copy_thread(0, clone_flags, stack_start, stack_size, p, regs); retval = copy_thread(0, clone_flags, stack_start, stack_size, p, regs);
if (retval) if (retval)