From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from abb.hmeau.com (abb.hmeau.com [144.6.53.87]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 25B8028E8; Sun, 25 Feb 2024 06:17:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=144.6.53.87 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708841846; cv=none; b=juB5+3xPwK1o1pk3A32cD3A41Cuqwlha7P4+svxc2xsFKAsK3kgFMf+V17aAZl05Sxrb6TLhtyiDzB8GkF3YCOF8n/nSTu3XEShUCBiFNhPhXzei6X+zvaZXtEydXFYwNQZRNC9AF1N9m07dGDlhDPvkVXvF3fUJ5j37AYDCuYI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708841846; c=relaxed/simple; bh=Vet3kNFNvQtLD/iQwxj+UEJSwFYFiQ2CtoXZP3rREUo=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=XF/FtMeupCcVU4Dd6Rvah1f/ojPNpZjic7ml47KpXikKufZPi+FlchBn7WLFG9FjdMSCD1qo5lw7MkS2ZxGgANcvuXZPj8i2j+m6wYqM9PpP9u092kMgvF4hQXXnEsn3dv/4yTHoszQsCoej/3kJ4Iw9l5Bgce/B6n7zqoJ8soY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=gondor.apana.org.au; spf=pass smtp.mailfrom=gondor.apana.org.au; arc=none smtp.client-ip=144.6.53.87 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=gondor.apana.org.au Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gondor.apana.org.au Received: from loth.rohan.me.apana.org.au ([192.168.167.2]) by formenos.hmeau.com with smtp (Exim 4.94.2 #2 (Debian)) id 1re7ov-00HW18-1n; Sun, 25 Feb 2024 14:17:06 +0800 Received: by loth.rohan.me.apana.org.au (sSMTP sendmail emulation); Sun, 25 Feb 2024 14:17:19 +0800 Date: Sun, 25 Feb 2024 14:17:19 +0800 From: Herbert Xu To: Kent Overstreet Cc: Matthew Wilcox , David Laight , "linux-kernel@vger.kernel.org" , Thomas Graf , "netdev@vger.kernel.org" , "linux-fsdevel@vger.kernel.org" , "maple-tree@lists.infradead.org" , "rcu@vger.kernel.org" Subject: Re: [PATCH 0/1] Rosebush, a new hash table Message-ID: References: <20240222203726.1101861-1-willy@infradead.org> <4a1416fcb3c547eb9612ce07da6a77ed@AcuMS.aculab.com> <2s73sed5n6kxg42xqceenjtcwxys4j2r5dc5x4fdtwkmhkw3go@7viy7qli43wd> <5p5sypt3y643rr7kp66lhmgksgtuvdgijrryh53mqiiqkrgyty@d4zcnya22owg> Precedence: bulk X-Mailing-List: rcu@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Sun, Feb 25, 2024 at 01:14:39AM -0500, Kent Overstreet wrote: > > it's a log curve - Yes it's O(log N/log log N). > chain length of 16 means you picked a bad hash > function. Or that someone is trying to attack you. The number 16 is the cut-off where we decide that someone has discovered our hash secret and can cause a particular to chain to grow without bound. At this point rhashtable will force a rehash with a different secret. Cheers, -- Email: Herbert Xu Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt