From: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
To: Zach Brown <zach.brown@oracle.com>
Cc: linux-kernel@vger.kernel.org,
Linus Torvalds <torvalds@linux-foundation.org>,
Ingo Molnar <mingo@elte.hu>, Ulrich Drepper <drepper@redhat.com>,
Arjan van de Ven <arjan@infradead.org>,
Andrew Morton <akpm@zip.com.au>,
Alan Cox <alan@lxorguk.ukuu.org.uk>,
"David S. Miller" <davem@davemloft.net>,
Suparna Bhattacharya <suparna@in.ibm.com>,
Davide Libenzi <davidel@xmailserver.org>,
Jens Axboe <jens.axboe@oracle.com>,
Thomas Gleixner <tglx@linutronix.de>,
Dan Williams <dan.j.williams@gmail.com>,
Jeff Moyer <jmoyer@redhat.com>,
Simon Holm Thogersen <odie@cs.aau.dk>,
suresh.b.siddha@intel.com
Subject: Re: [PATCH 5/6] syslets: add generic syslets infrastructure
Date: Fri, 7 Dec 2007 14:55:05 +0300 [thread overview]
Message-ID: <20071207115505.GA18013@2ka.mipt.ru> (raw)
In-Reply-To: <11969832192130-git-send-email-zach.brown@oracle.com>
Hi Zach.
On Thu, Dec 06, 2007 at 03:20:18PM -0800, Zach Brown (zach.brown@oracle.com) wrote:
> +/*
> + * XXX todo:
> + * - do we need all this '*cur = current' nonsense?
> + * - try to prevent userspace from submitting too much.. lazy user ptr read?
> + * - explain how to deal with waiting threads with stale data in current
> + * - how does userspace tell that a syslet completion was lost?
> + * provide an -errno argument to the userspace return function?
> + */
> +
> +/*
> + * These structs are stored on the kernel stack of tasks which are waiting to
> + * return to userspace. They are linked into their parent's list of syslet
> + * children stored in 'syslet_tasks' in the parent's task_struct.
> + */
> +struct syslet_task_entry {
> + struct task_struct *task;
> + struct list_head item;
> +};
> +
> +/*
> + * syslet_ring doesn't have any kernel-side storage. Userspace allocates them
> + * in their address space and initializes their fields and then passes them to
> + * the kernel.
> + *
> + * These hashes provide the kernel-side storage for the wait queues which
> + * sys_syslet_ring_wait() uses and the mutex which completion uses to serialize
> + * the (possible blocking) ordered writes of the completion and kernel head
> + * index into the ring.
> + *
> + * We chose the bucket that supports a given ring by hashing a u32 that
> + * userspace sets in the ring.
> + */
> +#define SYSLET_HASH_BITS (CONFIG_BASE_SMALL ? 4 : 8)
> +#define SYSLET_HASH_NR (1 << SYSLET_HASH_BITS)
> +#define SYSLET_HASH_MASK (SYSLET_HASH_NR - 1)
> +static wait_queue_head_t syslet_waitqs[SYSLET_HASH_NR];
> +static struct mutex syslet_muts[SYSLET_HASH_NR];
Why do you care about hashed tables scalability and not using trees?
--
Evgeniy Polyakov
next prev parent reply other threads:[~2007-12-07 12:06 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-12-06 23:20 syslets v7: back to basics Zach Brown
2007-12-06 23:20 ` [PATCH 1/6] indirect: use asmlinkage in i386 syscall table prototype Zach Brown
2007-12-06 23:20 ` [PATCH 2/6] syslet: asm-generic support to disable syslets Zach Brown
2007-12-06 23:20 ` [PATCH 3/6] syslet: introduce abi structs Zach Brown
2007-12-06 23:20 ` [PATCH 4/6] syslets: add indirect args Zach Brown
2007-12-06 23:20 ` [PATCH 5/6] syslets: add generic syslets infrastructure Zach Brown
2007-12-06 23:20 ` [PATCH 6/6] syslets: add both 32bit and 64bit x86 syslet support Zach Brown
2007-12-07 11:55 ` Evgeniy Polyakov [this message]
2007-12-07 18:24 ` [PATCH 5/6] syslets: add generic syslets infrastructure Zach Brown
2008-01-09 2:03 ` Rusty Russell
2008-01-09 3:00 ` Zach Brown
2008-01-09 3:48 ` Rusty Russell
2008-01-09 18:16 ` Zach Brown
2008-01-09 22:04 ` Rusty Russell
2008-01-09 22:58 ` Linus Torvalds
2008-01-09 23:05 ` Linus Torvalds
2008-01-09 23:47 ` Zach Brown
2008-01-10 1:18 ` Rusty Russell
2008-01-09 23:15 ` Davide Libenzi
2008-01-10 5:41 ` Jeff Garzik
2007-12-08 12:40 ` [PATCH 1/6] indirect: use asmlinkage in i386 syscall table prototype Simon Holm Thøgersen
2007-12-08 21:22 ` Zach Brown
2007-12-08 12:52 ` [PATCH] Fix casting on architectures with 32-bit pointers/longs Simon Holm Thøgersen
2007-12-10 19:46 ` syslets v7: back to basics Jens Axboe
2007-12-10 21:30 ` Phillip Susi
2007-12-10 22:15 ` Zach Brown
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