Date: Sun, 3 Feb 2008 07:49:11 +1100 From: Peter Jeremy <peterjeremy@optushome.com.au> To: Alexander Motin <mav@freebsd.org> Cc: freebsd-hackers@freebsd.org, freebsd-performance@freebsd.org Subject: Re: Memory allocation performance Message-ID: <20080202204911.GT35170@server.vk2pj.dyndns.org> In-Reply-To: <47A4CAFA.5040708@FreeBSD.org> References: <47A25412.3010301@FreeBSD.org> <47A25A0D.2080508@elischer.org> <47A2C2A2.5040109@FreeBSD.org> <20080201185435.X88034@fledge.watson.org> <47A43873.40801@FreeBSD.org> <20080202193656.GR35170@server.vk2pj.dyndns.org> <47A4CAFA.5040708@FreeBSD.org>
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--Zi0sgQQBxRFxMTsj Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Sat, Feb 02, 2008 at 09:56:42PM +0200, Alexander Motin wrote: >Peter Jeremy ?????: >> On Sat, Feb 02, 2008 at 11:31:31AM +0200, Alexander Motin wrote: >>> To check UMA dependency I have made a trivial one-element cache which i= n=20 >>> my test case allows to avoid two for four allocations per packet. >>=20 >> You should be able to implement this lockless using atomic(9). I haven't >> verified it, but the following should work. > >I have tried this, but man 9 atomic talks: > >The atomic_readandclear() functions are not implemented for the types >``char'', ``short'', ``ptr'', ``8'', and ``16'' and do not have any=20 >variants with memory barriers at this time. Hmmm. This seems to be more a documentation bug than missing code: atomic_readandclear_ptr() seems to be implemented on most architectures (the only one where I can't find it is arm) and is already used in malloc(3). --=20 Peter Jeremy Please excuse any delays as the result of my ISP's inability to implement an MTA that is either RFC2821-compliant or matches their claimed behaviour. --Zi0sgQQBxRFxMTsj Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.4 (FreeBSD) iD8DBQFHpNdH/opHv/APuIcRAjglAJ4xNZrFttUitci+60Q+GyVvdziGrQCaAkxf c2uNtF4tELpQ+7FHoc07LLY= =ZYY7 -----END PGP SIGNATURE----- --Zi0sgQQBxRFxMTsj--
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