From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 13 Jul 2004 16:35:25 -0500 From: Brent Casavant Reply-To: Brent Casavant Subject: Re: Scaling problem with shmem_sb_info->stat_lock In-Reply-To: Message-ID: References: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Hugh Dickins Cc: William Lee Irwin III , linux-mm@kvack.org List-ID: On Tue, 13 Jul 2004, Hugh Dickins wrote: > Though wli's per-cpu idea was sensible enough, converting to that > didn't appeal to me very much. We only have a limited amount of > per-cpu space, I think, but an indefinite number of tmpfs mounts. > Might be reasonable to allow per-cpu for 4 or them (the internal > one which is troubling you, /dev/shm, /tmp and one other). Tiresome. Per-CPU has the problem that the CPU on which you did a free_blocks++ might not be the same one where you do a free_blocks--. Bleh. Maybe using a hash indexed on some tid bits (pun unintended, but funny nevertheless) might work? But of course this suffers from the same class of problem as mentioned in the previous paragraph. > Yes, go ahead, though it's getting more and more embarrassing that I > started out reusing VM_ACCOUNT within shmem.c, it should now have its > own set of flags: let me tidy that up once you're done. Hmm. Guess that means I need to crack the whip on myself a bit... :) > But please don't call the new one SHMEM_NOACCT: ACCT or ACCOUNT refers > to the security_vm_enough_memory/vm_unacct_memory stuff throughout, > and _that_ accounting does still apply to these /dev/zero files. > > Hmm, I was about to suggest SHMEM_NOSBINFO, > but how about really no sbinfo, just NULL sbinfo? If you'd like me to try that, I sure can. The only problem is that I'm having a devil of a time figuring out where the struct super_block comes from for /dev/null -- or heck, if it's even distinct from any others. And the relationship between /dev/null and /dev/shm is still quite fuzzy as well. Oh the joy of being new to a chunk of code... Brent -- Brent Casavant bcasavan@sgi.com Forget bright-eyed and Operating System Engineer http://www.sgi.com/ bushy-tailed; I'm red- Silicon Graphics, Inc. 44.8562N 93.1355W 860F eyed and bushy-haired. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: aart@kvack.org