Hi Ted, > I understand why we would want to reduce this number. > Unfortunately, the question is what do we do if all 1024 threads try > to do buffered writes into the file system at the same instant, when > we have less than 4 megabytes of space left? > > The problem is that we can then do more writes than we have space, and > we will only find out about it at write back time, when the process > may have exited already -- at which point data loss is almost > inevitable. (We could keep the data in cache and frantically page > the system administrator to delete some files to make room for dirty > data, but that's probably not going to end well….) > > What we can do if we must clamp this threshold is to also increase the > threshold at which we shift away from delayed allocation. We'll then > allocate each block at write time, which does mean more CPU and > less efficient allocation of blocks, but if we're down to our last 4 > megabytes, there's probably not much we can do that will be efficient > as far as block layout anyway…. Thanks for the explanation, I'll go back and take another look. Anton -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
