BTS_BUFFER_SIZE
buffer = dsalloc_pages(BTS_BUFFER_SIZE, GFP_KERNEL | __GFP_NOWARN, cpu);
ds_update_cea(cea, buffer, BTS_BUFFER_SIZE, PAGE_KERNEL);
max = BTS_BUFFER_SIZE / BTS_RECORD_SIZE;
ds_clear_cea(cea, BTS_BUFFER_SIZE);
dsfree_pages(hwev->ds_bts_vaddr, BTS_BUFFER_SIZE);
char bts_buffer[BTS_BUFFER_SIZE];