Increasing the size of the buffer is expensive, as it comes from non pagedmemory that cannot be swapped out to disk, so keep the buffer as small as possible.
增加缓冲区大小的代价很高,因为它来自不能交换到磁碟的未分页记忆体,所以尽可能让缓冲区愈小愈好。
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The other problem with using this for larger buffers is that since it allocates non-pagedmemory, it would need to allocate a large block of sequential non-pagedmemory.