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Message-ID: <524f69650711101154s67e19fe6wa1803b8ded2ff632@mail.gmail.com> Date: Sat, 10 Nov 2007 13:54:44 -0600 From: "Steve French" <smfrench@...il.com> To: "Przemyslaw Wegrzyn" <czajnik@...jsoft.pl> Cc: "Andrew Morton" <akpm@...ux-foundation.org>, LKML <linux-kernel@...r.kernel.org>, joern@...fs.org, linux-cifs-client@...ts.samba.org Subject: Re: Fw: Buffer overflow in CIFS VFS. On Nov 10, 2007 7:03 AM, Przemyslaw Wegrzyn <czajnik@...jsoft.pl> wrote: > Steve French wrote: > > That might be better, although without memory pools, this would perform > > much worse > > > Why ? I don't get your point here. > > Przemyslaw > What I meant is that two fixed size memory pools rather variable size kmallocs helps performance. By using two fixed size buffers (small - which fits the typical smb request and response, and large which fits the maximum size request other than write which is handled via an iovec) and taking advantage of memory pools, cifs can always make progress even in low memory situations (reducing the likelihood of deadlock) and it reduces the number of times that cifs has to do the very expensive allocation of 16.5K. If cifs only used variable size request and response buffers, since they are frequently more than one page in size we would be forcing the memory manager to find contiguous pages which can be very slow. -- Thanks, Steve - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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