From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx179.postini.com [74.125.245.179]) by kanga.kvack.org (Postfix) with SMTP id EB5C56B004D for ; Thu, 10 May 2012 20:14:36 -0400 (EDT) Message-ID: <4FAC59F6.4080503@kernel.org> Date: Fri, 11 May 2012 09:14:46 +0900 From: Minchan Kim MIME-Version: 1.0 Subject: Re: [PATCH 3/4] zsmalloc use zs_handle instead of void * References: <4FA33DF6.8060107@kernel.org> <20120509201918.GA7288@kroah.com> <4FAB21E7.7020703@kernel.org> <20120510140215.GC26152@phenom.dumpdata.com> <4FABD503.4030808@vflare.org> <4FABDA9F.1000105@linux.vnet.ibm.com> <20120510151941.GA18302@kroah.com> <4FABECF5.8040602@vflare.org> <20120510164418.GC13964@kroah.com> <4FABF9D4.8080303@vflare.org> <20120510173322.GA30481@phenom.dumpdata.com> <4FAC4E3B.3030909@kernel.org> <8473859b-42f3-4354-b5ba-fd5b8cbac22f@default> In-Reply-To: <8473859b-42f3-4354-b5ba-fd5b8cbac22f@default> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Dan Magenheimer Cc: Konrad Wilk , Nitin Gupta , Greg Kroah-Hartman , Seth Jennings , Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org Hi Dan, On 05/11/2012 08:50 AM, Dan Magenheimer wrote: >> From: Minchan Kim [mailto:minchan@kernel.org] >> >> Okay. Now it works but zcache coupled with zsmalloc tightly. >> User of zsmalloc should never know internal of zs_handle. >> >> 3) >> >> - zsmalloc.h >> void *zs_handle_to_ptr(struct zs_handle handle) >> { >> return handle.hanle; >> } >> >> static struct zv_hdr *zv_create(..) >> { >> struct zs_handle handle; >> .. >> handle = zs_malloc(pool, size); >> .. >> return zs_handle_to_ptr(handle); >> } >> >> Why should zsmalloc support such interface? >> It's a zcache problem so it's desriable to solve it in zcache internal. >> And in future, if we can add/remove zs_handle's fields, we can't make >> sure such API. > > Hi Minchan -- > > I'm confused so maybe I am misunderstanding or you can > explain further. It seems like you are trying to redesign > zsmalloc so that it can be a pure abstraction in a library. > While I understand and value abstractions in software > designs, the primary use now of zsmalloc is in zcache. If > there are other users that require a different interface > or a more precise abstract API, zsmalloc could then > evolve to meet the needs of multiple users. But I think At least, zram is also primary user and it also has such mess although it's not severe than zcache. zram->table[index].handle sometime has real (void*) handle, sometime (struct page*). And I assume ramster you sent yesterday will be. I think there are already many mess and I bet it will prevent going to mainline. Especially, handle problem is severe because it a arguement of most functions exported in zsmalloc So, we should clean up before late, IMHO. > zcache is going to need more access to the internals > of its allocator, not less. Zsmalloc is currently missing > some important functionality that (I believe) will be > necessary to turn zcache into an enterprise-ready, If you have such TODO list, could you post it? It helps direction point of my stuff. > always-on kernel feature. If it evolves to add that > functionality, then it may no longer be able to provide > generic abstract access... in which case generic zsmalloc > may then have zero users in the kernel. Hmm, Do you want to make zsmalloc by zcache owned private allocator? > > So I'd suggest we hold off on trying to make zsmalloc > "pretty" until we better understand how it will be used > by zcache (and ramster) and, if there are any, any future > users. zcache isn't urgent? I'm okay about zcache but at least, zram is when it merged into mainline, I think. Many embedded system have a advantage with it so I hope we finish zsmalloc mess as soon as possble. > > That's just my opinion... Dan, Thanks for sharing your opinion. > Dan > > -- > 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/ . > Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ > Don't email: email@kvack.org > -- Kind regards, Minchan Kim -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org