On Monday, August 22, 2011 17:48:47 Anton Staaf wrote: > On Mon, Aug 22, 2011 at 2:42 PM, Wolfgang Denk wrote: > > Anton Staaf wrote: > >> Currently, if a device read request is done that does not begin or end > >> on a sector boundary a stack allocated bounce buffer is used to perform > >> the read, and then just the part of the sector that is needed is copied > >> into the users buffer. This stack allocation can mean that the bounce > >> buffer will not be aligned to the dcache line size. This is a problem > >> when caches are enabled because unaligned cache invalidates are not > >> safe. > >> > >> This patch allocates a cache line size aligned sector sized bounce > >> buffer the first time that ext2fs_devread is called. > > > > ...and never frees ist, which is a bad thing. Please fix. > > That was actually intentional. To free the buffer the code would need > to know when it was done doing ext2 accesses. This information isn't > really available. And it would be a performance hit to allocate and > free the buffer every time a read was performed, instead this patch > re-uses the same allocated buffer every time that the read is called. > Would you prefer that I allocate and free the buffer each time? I can > see an argument for that since it would mean that the code could also > be called from multiple threads simultaneously, not that we have any > such thing to worry about at the moment.
i'm not sure i follow ... the current code always frees it upon func exit. why cant yours do the same ? -mike
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