lkml.org 
[lkml]   [2006]   [Sep]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH 20/20] iscsi: support for swapping over iSCSI.
    Peter Zijlstra wrote:
    > Implement sht->swapdev() for iSCSI. This method takes care of reserving
    > the extra memory needed and marking all relevant sockets with SOCK_VMIO.
    >
    > When used for swapping, TCP socket creation is done under GFP_MEMALLOC and
    > the TCP connect is done with SOCK_VMIO to ensure their success. Also the
    > netlink userspace interface is marked SOCK_VMIO, this will ensure that even
    > under pressure we can still communicate with the daemon (which runs as
    > mlockall() and needs no additional memory to operate).
    >
    > Netlink requests are handled under the new PF_MEM_NOWAIT when a swapper is
    > present. This ensures that the netlink socket will not block. User-space will
    > need to retry failed requests.
    >
    > The TCP receive path is handled under PF_MEMALLOC for SOCK_VMIO sockets.
    > This makes sure we do not block the critical socket, and that we do not
    > fail to process incomming data.
    >
    > Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
    > CC: Mike Christie <michaelc@cs.wisc.edu>
    > ---
    > drivers/scsi/iscsi_tcp.c | 103 +++++++++++++++++++++++++++++++-----
    > drivers/scsi/scsi_transport_iscsi.c | 23 +++++++-
    > include/scsi/libiscsi.h | 1
    > include/scsi/scsi_transport_iscsi.h | 2
    > 4 files changed, 113 insertions(+), 16 deletions(-)
    >
    > Index: linux-2.6/drivers/scsi/iscsi_tcp.c
    > ===================================================================
    > --- linux-2.6.orig/drivers/scsi/iscsi_tcp.c
    > +++ linux-2.6/drivers/scsi/iscsi_tcp.c
    > @@ -42,6 +42,7 @@
    > #include <scsi/scsi_host.h>
    > #include <scsi/scsi.h>
    > #include <scsi/scsi_transport_iscsi.h>
    > +#include <scsi/scsi_device.h>
    >
    > #include "iscsi_tcp.h"
    >
    > @@ -845,9 +846,13 @@ iscsi_tcp_data_recv(read_descriptor_t *r
    > int rc;
    > struct iscsi_conn *conn = rd_desc->arg.data;
    > struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
    > - int processed;
    > + int processed = 0;
    > char pad[ISCSI_PAD_LEN];
    > struct scatterlist sg;
    > + unsigned long pflags = current->flags;
    > +
    > + if (sk_has_vmio(tcp_conn->sock->sk))
    > + current->flags |= PF_MEMALLOC;
    >

    Is this too late or not needed or what is it for? This function gets run
    from the network layer's softirq and at this point we have a skbuff with
    data that we want to process. The iscsi layer also does not allocate
    memory for read or write IO in this path.

    I think we would want to set this flag at a lower level. Something
    closer to where the skbuf is allocated?
    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2006-09-13 22:53    [W:0.022 / U:0.868 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site