[linux-lvm] LVM2 modifies the buffer_head struct?
Tom Walcott
tom_walcott at hotmail.com
Tue Jul 2 08:41:01 UTC 2002
Hello,
Browsing the patch submitted for 2.4 inclusion, I noticed that LVM2 modifies
the buffer_head struct. Why does LVM2 require the addition of it's own
private field in the buffer_head? It seems that it should be able to use the
existing b_private field.
How does that extra field affect performance relative to the cache? Won't
any negative effects be seen by everything that uses buffer_heads? Also, as
I understand the slab code and hardware cache alignment, won't the addition
of the new field cause the each buffer_head to consume 128 bytes instead of
96?
Just curious to know why this field was added, when the buffer_head already
had a field for this purpose.
-Tom
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