wrong list, sorry!
On Tue, Dec 6, 2011 at 1:29 PM, Yucong Sun (叶雨飞) <[email protected]> wrote: > Hi, > > I recently setup raid10 on 4 physical disk and have a iscsi serve it > as a block device, and have been trying to tweak for performance. > > First thing I notice that MD seems to rely on page cache to flush > changes to disk, is there any way to turn that off so changes are > flushed to the disk? like O_FSYNC|O_DIRECT does? The reason I want to > turn it off is to understand the performance difference, I want to be > sure that page cache is truly acting as a write-back cache, I know one > can tune the dirty_* to control the cache flush, but I want to make > sure that it is actually doing what I think it does. > > Then I notice in output of free, the number in Cache column is very > low, however the Buffer is very high, my question is does Buffer here > serves as a read cache? I couldn't find the answer anywhere else. > > My last question is that since MD seems already doing the cache, what > effect would it have if I want to setup a LO device in front of MD > device, Is there going to be more caching, how is different than just > plain MD device? > > Thanks. -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
