Ping? Has anyone glanced at this? On Fri, 2013-08-09 at 10:48 -0700, Frank Mayhar wrote: > The device mapper and some of its modules allocate memory pools at > various points when setting up a device. In some cases, these pools are > fairly large, for example the multipath module allocates a 256-entry > pool and the dm itself allocates three of that size. In a > memory-constrained environment where we're creating a lot of these > devices, the memory use can quickly become significant. Unfortunately, > there's currently no way to change the size of the pools other than by > changing a constant and rebuilding the kernel. > > This patch fixes that by changing the hardcoded MIN_IOS (and certain > other) #defines in dm-crypt, dm-io, dm-mpath, dm-snap and dm itself to > sysctl-modifiable values. This lets us change the size of these pools > on the fly, we can reduce the size of the pools and reduce memory > pressure. > > We tested performance of dm-mpath with smaller MIN_IOS sizes for both dm > and dm-mpath, from a value of 32 all the way down to zero. Bearing in > mind that the underlying devices were network-based, we saw essentially > no performance degradation; if there was any, it was down in the noise. > One might wonder why these sizes are the way they are; I investigated > and they've been unchanged since at least 2006. > > Signed-off-by: Frank Mayhar <fmay...@google.com>
-- Frank Mayhar 310-460-4042 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
