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From: ebiederm+eric@npwt.net (Eric W. Biederman)
To: Zlatko.Calusic@CARNet.hr
Cc: linux-mm@kvack.org
Subject: Re: Comments on shmfs-0.1.010
Date: 18 Jul 1998 11:03:10 -0500	[thread overview]
Message-ID: <m1r9zjjge9.fsf@flinx.npwt.net> (raw)
In-Reply-To: Zlatko Calusic's message of 18 Jul 1998 14:59:02 +0200

>>>>> "ZC" == Zlatko Calusic <Zlatko.Calusic@CARNet.hr> writes:

>> This is a normal case with no harm.  
>> I think normal 2.1.101 should cause it too.
>> It's simply a result of swapping adding swap.

ZC> Well, it looks like it's harmless. I don't know why. :)

In that case it is harmless because it is reading the first page of
swap onto the swap lock!  And since there are no races there the lock
isn't needed.

>> Are you creating really large files in shmfs?

ZC> Yes, I was creating very big file to test some things.

ZC> But after I applied my patch, I never saw those kmalloc messages?!

Currently all of pointers to file blocks are allocated just in kernel
memory.  So really big files might cause that.  I haven't seen them so
I haven't a clue.

ZC> Unfortunately not. Time for experimenting ran out. :(

Well that at least tells me which options were used to get those
performance marks.


ZC> Yesterday I tried to copy linux tree to /shm and got these errors:

ZC> Tree has around 4200 files (which is slightly more than inode limit on 
ZC> Linux!). Few last files didn't get copied.

The story is that I allocate a fixed number of inodes to shmfs at mount time.
And then when I need one I look through those structures for one that is unused.

That is fine for testing my kernel patch, but in the long run it is a problem.
The temporary work around is to due:
mount -t shmfs -o inodes=10240 none /tmp
Anything less than 65535 should be legal.

The raw development version has a fix for this and a few other things
that I allocate in kernel memory, but it isn't stable yet.  I'm using
the stable code to create my kernel patches.

Eric



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      reply	other threads:[~1998-07-18 15:50 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
1998-07-16 22:03 Zlatko Calusic
1998-07-18  0:50 ` Eric W. Biederman
1998-07-18 12:59   ` Zlatko Calusic
1998-07-18 16:03     ` Eric W. Biederman [this message]

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